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American football - Wikipedia

Source 2020: https://en.m.wikipedia.org/wiki/American_football | 2020-02-03

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					<h1 id="section_0">American football</h1>
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<div role="note" class="hatnote navigation-not-searchable">This article is about the American variation of gridiron football. For other uses, see <a href="/wiki/American_football_(disambiguation)" class="mw-disambig" title="American football (disambiguation)">American football (disambiguation)</a>.</div>
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<p><b>American football</b>, referred to as <b>football</b> in the United States and Canada and also known as <b>gridiron</b>,<sup id="cite_ref-4" class="reference"><a href="#cite_note-4">[nb 1]</a></sup> is a <a href="/wiki/Team_sport" title="Team sport">team sport</a> played by two teams of eleven players on a rectangular <a href="/wiki/American_football_field" title="American football field">field</a> with goalposts at each end. The <a href="/wiki/Offense_(sports)" title="Offense (sports)">offense</a>, the team with possession of the oval-shaped <a href="/wiki/Ball_(gridiron_football)" title="Ball (gridiron football)">football</a>, attempts to advance down the field by <a href="/wiki/Rush_(gridiron_football)" title="Rush (gridiron football)">running</a> with the ball or <a href="/wiki/Forward_pass#American_and_Canadian_football" title="Forward pass">passing</a> it, while the <a href="/wiki/Defense_(sports)" title="Defense (sports)">defense</a>, the team without possession of the ball, aims to stop the offense's advance and to take control of the ball for themselves. The offense must advance at least ten yards in four <a href="/wiki/Down_(gridiron_football)" title="Down (gridiron football)">downs</a> or plays; if they fail, they <a href="/wiki/Turnover_on_downs" title="Turnover on downs">turn over</a> the football to the defense, but if they succeed, they are given a new set of four downs to continue the <a href="/wiki/Glossary_of_American_football#drive" title="Glossary of American football">drive</a>. Points are scored primarily by advancing the ball into the opposing team's <a href="/wiki/End_zone" title="End zone">end zone</a> for a <a href="/wiki/Touchdown" title="Touchdown">touchdown</a> or kicking the ball through the opponent's goalposts for a <a href="/wiki/Field_goal" title="Field goal">field goal</a>. The team with the most points at the end of a game wins.
</p><table class="infobox vcard" style="width:22em"><caption class="fn" style="padding-bottom:0.2em;">American football</caption><tbody><tr><td colspan="2" style="text-align:center"><a href="/wiki/File:Larry_Fitzgerald_catches_TD_at_2009_Pro_Bowl.jpg" class="image"><img alt="Larry Fitzgerald catches TD at 2009 Pro Bowl.jpg" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Larry_Fitzgerald_catches_TD_at_2009_Pro_Bowl.jpg/250px-Larry_Fitzgerald_catches_TD_at_2009_Pro_Bowl.jpg" decoding="async" width="250" height="350" data-file-width="1500" data-file-height="2100"></a><div><a href="/wiki/Larry_Fitzgerald" title="Larry Fitzgerald">Larry Fitzgerald</a> (in blue) catches a pass while <a href="/wiki/Cortland_Finnegan" title="Cortland Finnegan">Cortland Finnegan</a> (in red) plays defense at the <a href="/wiki/2009_Pro_Bowl" title="2009 Pro Bowl">2009 Pro Bowl</a>.</div></td></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;">Highest <a href="/wiki/Sports_governing_body" title="Sports governing body">governing body</a></th><td style="line-height:1.3em;"><a href="/wiki/International_Federation_of_American_Football" title="International Federation of American Football">International Federation of American Football</a></td></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;">Nicknames</th><td style="line-height:1.3em;"><div class="hlist hlist-separated"><ul><li><a href="/wiki/Football_(word)" title="Football (word)">Football</a></li><li><a href="/wiki/Gridiron_football" title="Gridiron football">gridiron</a></li></ul></div></td></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;">First played</th><td style="line-height:1.3em;"><a href="/wiki/1869_New_Jersey_vs._Rutgers_football_game" title="1869 New Jersey vs. Rutgers football game">November 6, 1869</a><br><a href="/wiki/New_Brunswick,_New_Jersey" title="New Brunswick, New Jersey">New Brunswick, New Jersey</a>, United States<br>(<a href="/wiki/Princeton_Tigers_football" title="Princeton Tigers football">Princeton</a> vs. <a href="/wiki/Rutgers_Scarlet_Knights_football" title="Rutgers Scarlet Knights football">Rutgers</a>)</td></tr><tr><th colspan="2" style="text-align:center;background:#eee;">Characteristics</th></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;">Contact</th><td style="line-height:1.3em;"><a href="/wiki/Contact_sport#Full-contact" title="Contact sport">Full-contact</a></td></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;">Team members</th><td style="line-height:1.3em;">11 (both teams may <a href="/wiki/Free_substitution" title="Free substitution">freely</a> <a href="/wiki/Substitution_(sport)" title="Substitution (sport)">substitute</a> players between downs)</td></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;">Type</th><td style="line-height:1.3em;"><div class="hlist hlist-separated"><ul><li><a href="/wiki/Team_sport" title="Team sport">Team sport</a></li><li><a href="/wiki/Ball_game" title="Ball game">ball game</a></li></ul></div></td></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;">Equipment</th><td style="line-height:1.3em;"><div class="plainlist">
<ul><li><a href="/wiki/Ball_(gridiron_football)" title="Ball (gridiron football)">Football</a></li>
<li><a href="/wiki/Football_helmet" title="Football helmet">Football helmet</a></li>
<li><a href="/wiki/Padding" title="Padding">Pads</a> (<a href="/wiki/Shoulder_pads" title="Shoulder pads">shoulder</a> and <a href="/wiki/Knee_pads" class="mw-redirect" title="Knee pads">knee</a>)</li></ul></div></td></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;">Venue</th><td style="line-height:1.3em;"><a href="#Field_and_equipment">Football field</a> (rectangular: 120 yards long, 53 ​<span class="frac nowrap"><sup>1</sup>⁄<sub>3</sub></span> yards wide)</td></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;">Glossary</th><td style="line-height:1.3em;"><a href="/wiki/Glossary_of_American_football" title="Glossary of American football">Glossary of American football</a></td></tr><tr><th colspan="2" style="text-align:center;background:#eee;">Presence</th></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;">Country or region</th><td style="line-height:1.3em;">Worldwide</td></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;"><a href="/wiki/Olympic_Games" title="Olympic Games">Olympic</a></th><td style="line-height:1.3em;">No (<a href="/wiki/Demonstration_sport" title="Demonstration sport">demonstrated</a> at the <a href="/wiki/American_football_at_the_1932_Summer_Olympics" title="American football at the 1932 Summer Olympics">1932 Summer Olympics</a>)<sup id="cite_ref-Football_remains_an_Olympic_long_shot_1-0" class="reference"><a href="#cite_note-Football_remains_an_Olympic_long_shot-1">[1]</a></sup></td></tr><tr><th scope="row" style="padding-top:0.2em;line-height:1.2em; padding-right:1.0em;"><a href="/wiki/World_Games" title="World Games">World Games</a></th><td style="line-height:1.3em;">Yes (invitational sport at <a href="/wiki/American_football_at_the_2005_World_Games" title="American football at the 2005 World Games">2005</a> and <a href="/wiki/American_football_at_the_2017_World_Games" title="American football at the 2017 World Games">2017</a> Games).</td></tr></tbody></table><p>American football evolved in the United States, originating from the sports of <a href="/wiki/Association_football" title="Association football">soccer</a> and <a href="/wiki/Rugby_football" title="Rugby football">rugby</a>. The first American football match was played on <a href="/wiki/1869_New_Jersey_vs._Rutgers_football_game" title="1869 New Jersey vs. Rutgers football game">November 6, 1869</a>, between two college teams, <a href="/wiki/Rutgers_Scarlet_Knights_football" title="Rutgers Scarlet Knights football">Rutgers</a> and <a href="/wiki/Princeton_Tigers_football" title="Princeton Tigers football">Princeton</a>, using rules based on the rules of soccer at the time. A set of rule changes drawn up from <a href="/wiki/1880_college_football_season" title="1880 college football season">1880</a> onward by <a href="/wiki/Walter_Camp" title="Walter Camp">Walter Camp</a>, the "Father of American Football", established the <a href="/wiki/Snap_(gridiron_football)" title="Snap (gridiron football)">snap</a>, the <a href="/wiki/Line_of_scrimmage" title="Line of scrimmage">line of scrimmage</a>, eleven-player teams, and the concept of downs. Later rule changes legalized the <a href="/wiki/Forward_pass" title="Forward pass">forward pass</a>, created the <a href="/wiki/Neutral_zone_(gridiron_football)" title="Neutral zone (gridiron football)">neutral zone</a> and specified the size and shape of the football. The sport <a href="/wiki/Comparison_of_American_and_Canadian_football" title="Comparison of American and Canadian football">is closely related</a> to <a href="/wiki/Canadian_football" title="Canadian football">Canadian football</a>, which evolved in parallel with and at the same time as the American game (although their rules were <a href="/wiki/Burnside_rules" title="Burnside rules">developed independently</a> from that of Camp's). Most of the features that distinguish American football from rugby and soccer are also present in Canadian football. The two sports are considered the primary variants of <a href="/wiki/Gridiron_football" title="Gridiron football">gridiron football</a>.
</p><p>American football is the most popular <a href="/wiki/Sport_in_the_United_States" class="mw-redirect" title="Sport in the United States">sport in the United States</a>. The most popular forms of the game are <a href="/wiki/Professional_football_(gridiron)" title="Professional football (gridiron)">professional</a> and <a href="/wiki/College_football" title="College football">college football</a>, with the other major levels being <a href="/wiki/High_school_football" title="High school football">high school</a> and youth football. As of 2012<sup class="plainlinks noexcerpt noprint asof-tag update" style="display:none;"><a class="external text" href="https://en.wikipedia.org/w/index.php?title=American_football&action=edit">[update]</a></sup>, nearly 1.1 million high school athletes and 70,000 college athletes play the sport in the United States annually. The <a href="/wiki/National_Football_League" title="National Football League">National Football League</a>, the most popular American football league, has the <a href="/wiki/List_of_sports_attendance_figures#Top_leagues_in_total_attendance" title="List of sports attendance figures">highest average attendance of any professional sports league in the world</a>. Its championship game, the <a href="/wiki/Super_Bowl" title="Super Bowl">Super Bowl</a>, ranks among the most-watched club sporting events in the world. The league has an annual revenue of around US$10 billion. Other leagues exist worldwide, but the sport does not have the international popularity of other American sports like <a href="/wiki/Baseball" title="Baseball">baseball</a> or <a href="/wiki/Basketball" title="Basketball">basketball</a>.
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<div id="toc" class="toc"><input type="checkbox" role="button" id="toctogglecheckbox" class="toctogglecheckbox" style="display:none"><div class="toctitle" lang="en" dir="ltr"><h2>Contents</h2><span class="toctogglespan"><label class="toctogglelabel" for="toctogglecheckbox"></label></span></div>
<ul><li class="toclevel-1 tocsection-1"><a href="#Etymology_and_names"><span class="tocnumber">1</span> <span class="toctext">Etymology and names</span></a></li>
<li class="toclevel-1 tocsection-2"><a href="#History"><span class="tocnumber">2</span> <span class="toctext">History</span></a>
<ul><li class="toclevel-2 tocsection-3"><a href="#Early_history"><span class="tocnumber">2.1</span> <span class="toctext">Early history</span></a></li>
<li class="toclevel-2 tocsection-4"><a href="#Evolution_of_the_game"><span class="tocnumber">2.2</span> <span class="toctext">Evolution of the game</span></a></li>
<li class="toclevel-2 tocsection-5"><a href="#Professional_era"><span class="tocnumber">2.3</span> <span class="toctext">Professional era</span></a></li>
</ul></li>
<li class="toclevel-1 tocsection-6"><a href="#Teams_and_positions"><span class="tocnumber">3</span> <span class="toctext">Teams and positions</span></a>
<ul><li class="toclevel-2 tocsection-7"><a href="#Offensive_unit"><span class="tocnumber">3.1</span> <span class="toctext">Offensive unit</span></a></li>
<li class="toclevel-2 tocsection-8"><a href="#Defensive_unit"><span class="tocnumber">3.2</span> <span class="toctext">Defensive unit</span></a></li>
<li class="toclevel-2 tocsection-9"><a href="#Special_teams_unit"><span class="tocnumber">3.3</span> <span class="toctext">Special teams unit</span></a></li>
</ul></li>
<li class="toclevel-1 tocsection-10"><a href="#Rules"><span class="tocnumber">4</span> <span class="toctext">Rules</span></a>
<ul><li class="toclevel-2 tocsection-11"><a href="#Scoring"><span class="tocnumber">4.1</span> <span class="toctext">Scoring</span></a></li>
<li class="toclevel-2 tocsection-12"><a href="#Field_and_equipment"><span class="tocnumber">4.2</span> <span class="toctext">Field and equipment</span></a></li>
<li class="toclevel-2 tocsection-13"><a href="#Duration_and_time_stoppages"><span class="tocnumber">4.3</span> <span class="toctext">Duration and time stoppages</span></a></li>
<li class="toclevel-2 tocsection-14"><a href="#Advancing_the_ball_and_downs"><span class="tocnumber">4.4</span> <span class="toctext">Advancing the ball and downs</span></a></li>
<li class="toclevel-2 tocsection-15"><a href="#Kicking"><span class="tocnumber">4.5</span> <span class="toctext">Kicking</span></a></li>
<li class="toclevel-2 tocsection-16"><a href="#Officials_and_fouls"><span class="tocnumber">4.6</span> <span class="toctext">Officials and fouls</span></a></li>
</ul></li>
<li class="toclevel-1 tocsection-17"><a href="#Safety_and_brain_health"><span class="tocnumber">5</span> <span class="toctext">Safety and brain health</span></a></li>
<li class="toclevel-1 tocsection-18"><a href="#Leagues_and_tournaments"><span class="tocnumber">6</span> <span class="toctext">Leagues and tournaments</span></a>
<ul><li class="toclevel-2 tocsection-19"><a href="#Other_professional_leagues"><span class="tocnumber">6.1</span> <span class="toctext">Other professional leagues</span></a>
<ul><li class="toclevel-3 tocsection-20"><a href="#Rival_leagues"><span class="tocnumber">6.1.1</span> <span class="toctext">Rival leagues</span></a></li>
<li class="toclevel-3 tocsection-21"><a href="#Complementary_national_leagues"><span class="tocnumber">6.1.2</span> <span class="toctext">Complementary national leagues</span></a></li>
</ul></li>
<li class="toclevel-2 tocsection-22"><a href="#International_play"><span class="tocnumber">6.2</span> <span class="toctext">International play</span></a></li>
</ul></li>
<li class="toclevel-1 tocsection-23"><a href="#Popularity_and_cultural_impact"><span class="tocnumber">7</span> <span class="toctext">Popularity and cultural impact</span></a>
<ul><li class="toclevel-2 tocsection-24"><a href="#United_States"><span class="tocnumber">7.1</span> <span class="toctext">United States</span></a></li>
<li class="toclevel-2 tocsection-25"><a href="#Other_countries"><span class="tocnumber">7.2</span> <span class="toctext">Other countries</span></a></li>
</ul></li>
<li class="toclevel-1 tocsection-26"><a href="#Variations_and_related_sports"><span class="tocnumber">8</span> <span class="toctext">Variations and related sports</span></a></li>
<li class="toclevel-1 tocsection-27"><a href="#See_also"><span class="tocnumber">9</span> <span class="toctext">See also</span></a></li>
<li class="toclevel-1 tocsection-28"><a href="#Notes"><span class="tocnumber">10</span> <span class="toctext">Notes</span></a></li>
<li class="toclevel-1 tocsection-29"><a href="#Footnotes"><span class="tocnumber">11</span> <span class="toctext">Footnotes</span></a></li>
<li class="toclevel-1 tocsection-30"><a href="#References"><span class="tocnumber">12</span> <span class="toctext">References</span></a></li>
<li class="toclevel-1 tocsection-31"><a href="#Further_reading"><span class="tocnumber">13</span> <span class="toctext">Further reading</span></a></li>
<li class="toclevel-1 tocsection-32"><a href="#External_links"><span class="tocnumber">14</span> <span class="toctext">External links</span></a></li>
</ul></div>

</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(1)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="Etymology_and_names">Etymology and names</span></h2><section class="mf-section-1 collapsible-block" id="mf-section-1">
<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Football_(word)" title="Football (word)">Football (word)</a></div>
<p>In the United States, American football is referred to as "football".<sup id="cite_ref-Football_Or_Soccer?_What’s_In_A_Name?_5-0" class="reference"><a href="#cite_note-Football_Or_Soccer?_What%E2%80%99s_In_A_Name?-5">[4]</a></sup> The term "football" was officially established in the rulebook for the <a href="/wiki/1876_college_football_season" title="1876 college football season">1876 college football season</a>, when the sport first shifted from soccer-style rules to rugby-style rules. Although it could easily have been called "rugby" at this point, Harvard, one of the primary proponents of the rugby-style game, compromised and did not request the name of the sport be changed to "rugby".<sup id="cite_ref-6" class="reference"><a href="#cite_note-6">[5]</a></sup> The terms "<a href="/wiki/Gridiron_football" title="Gridiron football">gridiron</a>" or "American football" are favored in English-speaking countries where other types of <a href="/wiki/Football_(word)" title="Football (word)">football</a> are popular, such as the United Kingdom, Ireland, New Zealand, and Australia.<sup id="cite_ref-'In_the_six'_and_football's_other_strange_Americanisms_7-0" class="reference"><a href="#cite_note-'In_the_six'_and_football's_other_strange_Americanisms-7">[6]</a></sup><sup id="cite_ref-Living_off_the_grid:_American_football_in_coastal_Australia_8-0" class="reference"><a href="#cite_note-Living_off_the_grid:_American_football_in_coastal_Australia-8">[7]</a></sup></p>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(2)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="History">History</span></h2><section class="mf-section-2 collapsible-block" id="mf-section-2">
<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/History_of_American_football" title="History of American football">History of American football</a></div>
<h3 class="in-block"><span class="mw-headline" id="Early_history">Early history</span></h3>
<p>American football evolved from the sports of <a href="/wiki/Association_football" title="Association football">soccer</a> and <a href="/wiki/Rugby_football" title="Rugby football">rugby</a>. Rugby, like American football, is a sport where two competing teams vie for control of a ball, which can be kicked through a set of goalposts or run into the opponent's goal area to score points.<sup id="cite_ref-The_basics_of_rugby_union_9-0" class="reference"><a href="#cite_note-The_basics_of_rugby_union-9">[8]</a></sup></p><p>What is considered to be the first American football game was played on <a href="/wiki/1869_New_Jersey_vs._Rutgers_football_game" title="1869 New Jersey vs. Rutgers football game">November 6, 1869</a>, between <a href="/wiki/Rutgers_Scarlet_Knights_football" title="Rutgers Scarlet Knights football">Rutgers</a> and <a href="/wiki/Princeton_Tigers_football" title="Princeton Tigers football">Princeton</a>, two college teams. They consisted of 25 players each and used a round ball that could not be picked up or carried. It could, however, be kicked or batted with the feet, hands, head or sides, with the objective being to advance it into the opponent's goal. Rutgers won the game 6–4.<sup id="cite_ref-Rutgers_10-0" class="reference"><a href="#cite_note-Rutgers-10">[9]</a></sup><sup id="cite_ref-No_Christian_End_11-0" class="reference"><a href="#cite_note-No_Christian_End-11">[10]</a></sup> Collegiate play continued for several years with matches played using the rules of the host school. Representatives of Yale, <a href="/wiki/Columbia_University" title="Columbia University">Columbia</a>, Princeton and Rutgers met on October 19, 1873, to create a standard set of rules for use by all schools. Teams were set at 20 players each, and fields of 400 by 250 feet (122 m × 76 m) were specified. Harvard abstained from the conference, as they favored a rugby-style game that allowed running with the ball.<sup id="cite_ref-No_Christian_End_11-1" class="reference"><a href="#cite_note-No_Christian_End-11">[10]</a></sup> After playing <a href="/wiki/McGill_University" title="McGill University">McGill University</a> using both Canadian and American rules, the Harvard players preferred the Canadian style of having only 11 men on the field, running the ball without having to be chased by an opponent, the forward pass, tackling, and using an oblong instead of a round ball.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12">[11]</a></sup><sup id="cite_ref-13" class="reference"><a href="#cite_note-13">[12]</a></sup></p><p>An 1875 Harvard–Yale game played under rugby-style rules was observed by two Princeton athletes who were impressed by it. They introduced the sport to Princeton, a feat the <a href="/wiki/Professional_Football_Researchers_Association" title="Professional Football Researchers Association">Professional Football Researchers Association</a> compared to "selling <a href="/wiki/Refrigerator" title="Refrigerator">refrigerators</a> to <a href="/wiki/Eskimo" title="Eskimo">Eskimos</a>".<sup id="cite_ref-No_Christian_End_11-2" class="reference"><a href="#cite_note-No_Christian_End-11">[10]</a></sup> Princeton, Harvard, Yale, and Columbia then agreed to intercollegiate play using a form of <a href="/wiki/Rugby_union" title="Rugby union">rugby union</a> rules with a modified scoring system.<sup id="cite_ref-Camp_and_His_Followers_14-0" class="reference"><a href="#cite_note-Camp_and_His_Followers-14">[13]</a></sup> These schools formed the <a href="/wiki/Intercollegiate_Football_Association" title="Intercollegiate Football Association">Intercollegiate Football Association</a>, although Yale did not join until 1879. Yale player <a href="/wiki/Walter_Camp" title="Walter Camp">Walter Camp</a>, now regarded as the "Father of American Football",<sup id="cite_ref-Camp_and_His_Followers_14-1" class="reference"><a href="#cite_note-Camp_and_His_Followers-14">[13]</a></sup><sup id="cite_ref-NFL1869_15-0" class="reference"><a href="#cite_note-NFL1869-15">[14]</a></sup> secured rule changes in 1880 that reduced the size of each team from 15 to 11 players and instituted the <a href="/wiki/Snap_(gridiron_football)" title="Snap (gridiron football)">snap</a> to replace the chaotic and inconsistent <a href="/wiki/Scrum_(rugby)" title="Scrum (rugby)">scrum</a>.<sup id="cite_ref-Camp_and_His_Followers_14-2" class="reference"><a href="#cite_note-Camp_and_His_Followers-14">[13]</a></sup></p>
<h3 class="in-block"><span class="mw-headline" id="Evolution_of_the_game">Evolution of the game</span></h3>
<div class="thumb tleft"><div class="thumbinner" style="width:172px;"><a href="/wiki/File:Walter_Camp_-_Project_Gutenberg_eText_18048.jpg" class="image"><noscript><img alt="Walter Camp standing by the railing on a bridge" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/30/Walter_Camp_-_Project_Gutenberg_eText_18048.jpg/170px-Walter_Camp_-_Project_Gutenberg_eText_18048.jpg" decoding="async" width="170" height="284" class="thumbimage" data-file-width="400" data-file-height="668"></noscript><span class="lazy-image-placeholder" style="width: 170px;height: 284px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/3/30/Walter_Camp_-_Project_Gutenberg_eText_18048.jpg/170px-Walter_Camp_-_Project_Gutenberg_eText_18048.jpg" data-alt="Walter Camp standing by the railing on a bridge" data-width="170" data-height="284" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:Walter_Camp_-_Project_Gutenberg_eText_18048.jpg" class="internal" title="Enlarge"></a></div>A photograph of <a href="/wiki/Walter_Camp" title="Walter Camp">Walter Camp</a>, the "Father of American Football", taken in 1878 when Camp was captain of <a href="/wiki/Yale" class="mw-redirect" title="Yale">Yale</a>'s football team</div></div></div>
<p>The introduction of the snap resulted in an unexpected consequence. Prior to the snap, the strategy had been to punt if a scrum resulted in bad field position. However, a group of Princeton players realized that as the snap was uncontested, they could now hold the ball indefinitely to prevent their opponent from scoring. In 1881, in a game between Yale and Princeton, both teams used this strategy to maintain their undefeated records. Each team held the ball, gaining no ground, for an entire half, resulting in a 0–0 tie. This "block game" proved extremely unpopular with both teams' spectators and fans.<sup id="cite_ref-Camp_and_His_Followers_14-3" class="reference"><a href="#cite_note-Camp_and_His_Followers-14">[13]</a></sup></p><p>A rule change was necessary to prevent this strategy from taking hold, and a reversion to the scrum was considered. However, Camp successfully proposed a rule in 1882 that limited each team to three <a href="/wiki/Down_(gridiron_football)" title="Down (gridiron football)">downs</a>, or tackles, to advance the ball 5 yards (4.6 m). Failure to advance the ball the required distance within those three downs would result in control of the ball being forfeited to the other team. This change effectively made American football a separate sport from rugby, and the resulting five-yard lines added to the field to measure distances made it resemble a <a href="/wiki/Gridiron_(cooking)" title="Gridiron (cooking)">gridiron</a> in appearance. Other major rule changes included a reduction of the field size to 110 by <span class="frac nowrap">53<span class="visualhide"> </span><sup>1</sup>⁄<sub>3</sub></span> yards (100.6 m × 48.8 m) and the adoption of a scoring system that awarded four points for a touchdown, two for a safety and a <a href="/wiki/Conversion_(gridiron_football)" title="Conversion (gridiron football)">goal following a touchdown</a>, and five for a <a href="/wiki/Field_goal_(American_and_Canadian_football)" class="mw-redirect" title="Field goal (American and Canadian football)">goal from the field</a>. Additionally, tackling below the waist was legalized,<sup id="cite_ref-Camp_and_His_Followers_14-4" class="reference"><a href="#cite_note-Camp_and_His_Followers-14">[13]</a></sup> and a static <a href="/wiki/Line_of_scrimmage" title="Line of scrimmage">line of scrimmage</a> was instituted.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16">[15]</a></sup></p>
<div class="thumb tright"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:WCMorris_Spokesman-Review_cartoons_099_(1).jpg" class="image"><noscript><img alt="Cartoon showing a figure with a skeletal head holding a football upright with extended arms while lying down on a football field" src="//upload.wikimedia.org/wikipedia/commons/thumb/c/ca/WCMorris_Spokesman-Review_cartoons_099_%281%29.jpg/220px-WCMorris_Spokesman-Review_cartoons_099_%281%29.jpg" decoding="async" width="220" height="166" class="thumbimage" data-file-width="1152" data-file-height="867"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 166px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/c/ca/WCMorris_Spokesman-Review_cartoons_099_%281%29.jpg/220px-WCMorris_Spokesman-Review_cartoons_099_%281%29.jpg" data-alt="Cartoon showing a figure with a skeletal head holding a football upright with extended arms while lying down on a football field" data-width="220" data-height="166" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:WCMorris_Spokesman-Review_cartoons_099_(1).jpg" class="internal" title="Enlarge"></a></div>1908 cartoon (by <a href="/wiki/William_Charles_Morris" title="William Charles Morris">W.C. Morris</a>) highlighting the dangers that were associated with the sport</div></div></div>
<p>Despite these new rules, football remained a violent sport. Dangerous mass-formations like the <a href="/wiki/Flying_wedge" title="Flying wedge">flying wedge</a> resulted in serious injuries and deaths.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17">[16]</a></sup> A 1905 peak of 19 fatalities nationwide resulted in a threat by President <a href="/wiki/Theodore_Roosevelt" title="Theodore Roosevelt">Theodore Roosevelt</a> to abolish the game unless major changes were made.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18">[17]</a></sup> In response, 62 colleges and universities met in New York City to discuss rule changes on December 28, 1905. These proceedings resulted in the formation of the Intercollegiate Athletic Association of the United States, later renamed the <a href="/wiki/National_Collegiate_Athletic_Association" title="National Collegiate Athletic Association">National Collegiate Athletic Association</a> (NCAA).<sup id="cite_ref-NCAA_19-0" class="reference"><a href="#cite_note-NCAA-19">[18]</a></sup></p><p>The legal <a href="/wiki/Forward_pass" title="Forward pass">forward pass</a> was introduced in 1906, although its impact was initially minimal due to the restrictions placed on its use. The idea of a 40-yard-wider field was opposed by Harvard due to the size of the new <a href="/wiki/Harvard_Stadium#Impact_on_American_Football" title="Harvard Stadium">Harvard Stadium</a>.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20">[19]</a></sup> Other rule changes introduced that year included the reduction of playing time from 70 to 60 minutes and an increase of the distance required for a first down from 5 to 10 yards (4.6 to 9.1 m). To reduce infighting and dirty play between teams, the <a href="/wiki/Neutral_zone_(gridiron_football)" title="Neutral zone (gridiron football)">neutral zone</a> was created along the width of the football before the snap.<sup id="cite_ref-Blondy_Wallace_and_the_Biggest_Football_Scandal_Ever:_1906_21-0" class="reference"><a href="#cite_note-Blondy_Wallace_and_the_Biggest_Football_Scandal_Ever:_1906-21">[20]</a></sup> Scoring was also adjusted: points awarded for field goals were reduced to three in 1909<sup id="cite_ref-NFL1869_15-1" class="reference"><a href="#cite_note-NFL1869-15">[14]</a></sup> and points for touchdowns were raised to six in 1912.<sup id="cite_ref-NFL1911_22-0" class="reference"><a href="#cite_note-NFL1911-22">[21]</a></sup> The field was also shortened to 100 yards (91 m) long, but two 10-yard-long (9.1 m) end zones were created, and teams were given four downs instead of three to advance the ball 10 yards (9.1 m).<sup id="cite_ref-Danzig1956_23-0" class="reference"><a href="#cite_note-Danzig1956-23">[22]</a></sup> The <a href="/wiki/Roughing_the_passer" title="Roughing the passer">roughing the passer</a> penalty was implemented in 1914, and eligible players were first allowed to catch the ball anywhere on the field in 1918.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24">[23]</a></sup></p>
<h3 class="in-block"><span class="mw-headline" id="Professional_era">Professional era</span></h3>
<div class="thumb tright"><div class="thumbinner" style="width:202px;"><a href="/wiki/File:Pudge_heffelfinger.jpg" class="image"><noscript><img alt="Photo of William Heffelfinger" src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e5/Pudge_heffelfinger.jpg/200px-Pudge_heffelfinger.jpg" decoding="async" width="200" height="273" class="thumbimage" data-file-width="233" data-file-height="318"></noscript><span class="lazy-image-placeholder" style="width: 200px;height: 273px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e5/Pudge_heffelfinger.jpg/200px-Pudge_heffelfinger.jpg" data-alt="Photo of William Heffelfinger" data-width="200" data-height="273" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:Pudge_heffelfinger.jpg" class="internal" title="Enlarge"></a></div><a href="/wiki/Pudge_Heffelfinger" title="Pudge Heffelfinger">Pudge Heffelfinger</a>, widely regarded as the first professional football player</div></div></div>
<div class="thumb tright"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:Indiana_Soldier%27s_and_Sailor%27s_Home_football_team,_1896.jpg" class="image"><noscript><img alt="A group of boys seated on stairs" src="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Indiana_Soldier%27s_and_Sailor%27s_Home_football_team%2C_1896.jpg/220px-Indiana_Soldier%27s_and_Sailor%27s_Home_football_team%2C_1896.jpg" decoding="async" width="220" height="176" class="thumbimage" data-file-width="5958" data-file-height="4759"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 176px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Indiana_Soldier%27s_and_Sailor%27s_Home_football_team%2C_1896.jpg/220px-Indiana_Soldier%27s_and_Sailor%27s_Home_football_team%2C_1896.jpg" data-alt="A group of boys seated on stairs" data-width="220" data-height="176" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:Indiana_Soldier%27s_and_Sailor%27s_Home_football_team,_1896.jpg" class="internal" title="Enlarge"></a></div>A team from the <a href="/wiki/Indiana_Soldiers%27_and_Sailors%27_Children%27s_Home" title="Indiana Soldiers' and Sailors' Children's Home">Indiana Soldiers' and Sailors' Children's Home</a>, 1896.</div></div></div>
<p>On November 12, 1892, <a href="/wiki/Pudge_Heffelfinger" title="Pudge Heffelfinger">Pudge Heffelfinger</a> was paid $500 to play a game for the <a href="/wiki/Allegheny_Athletic_Association" title="Allegheny Athletic Association">Allegheny Athletic Association</a> in a match against the <a href="/wiki/Pittsburgh_Athletic_Club_(football)" title="Pittsburgh Athletic Club (football)">Pittsburgh Athletic Club</a>. This is the first recorded instance of a player being <a href="/wiki/Professional_football_(gridiron)" title="Professional football (gridiron)">paid to participate in a game of American football</a>, although many athletic clubs in the 1880s offered indirect benefits, such as helping players attain employment, giving out trophies or watches that players could pawn for money, or paying double in expense money. Despite these extra benefits, the game had a strict sense of amateurism at the time, and direct payment to players was frowned upon, if not prohibited outright.<sup id="cite_ref-birth_25-0" class="reference"><a href="#cite_note-birth-25">[24]</a></sup></p><p>Over time, professional play became increasingly common, and with it came rising salaries and unpredictable player movement, as well as the illegal payment of college players who were still in school. The <a href="/wiki/National_Football_League" title="National Football League">National Football League</a> (NFL), a group of professional teams that was originally established in 1920 as the American Professional Football Association, aimed to solve these problems. This new league's stated goals included an end to bidding wars over players, prevention of the use of college players, and abolition of the practice of paying players to leave another team.<sup id="cite_ref-The_First_25_Years_26-0" class="reference"><a href="#cite_note-The_First_25_Years-26">[25]</a></sup> By 1922, the NFL had established itself as America's premier professional football league.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27">[26]</a></sup></p><p>The dominant form of football at the time was played at the <a href="/wiki/College_football" title="College football">collegiate level</a>. The upstart NFL received a boost to its legitimacy in 1925, however, when an NFL team, the <a href="/wiki/Pottsville_Maroons" title="Pottsville Maroons">Pottsville Maroons</a>, defeated a team of <a href="/wiki/Notre_Dame_Fighting_Irish_football" title="Notre Dame Fighting Irish football">Notre Dame</a> all-stars in an <a href="/wiki/1925_NFL_Championship_controversy#Background" title="1925 NFL Championship controversy">exhibition game</a>.<sup id="cite_ref-The_Curse_28-0" class="reference"><a href="#cite_note-The_Curse-28">[27]</a></sup> A greater emphasis on the passing game helped professional football to distinguish itself further from the college game during the late 1930s.<sup id="cite_ref-The_First_25_Years_26-1" class="reference"><a href="#cite_note-The_First_25_Years-26">[25]</a></sup> Football, in general, became increasingly popular following the <a href="/wiki/1958_NFL_Championship_game" class="mw-redirect" title="1958 NFL Championship game">1958 NFL Championship game</a>, a match between the <a href="/wiki/Baltimore_Colts" class="mw-redirect" title="Baltimore Colts">Baltimore Colts</a> and the <a href="/wiki/New_York_Giants" title="New York Giants">New York Giants</a> that is still referred to as the "Greatest Game Ever Played". The game, a 23–17 overtime victory by the Colts, was seen by millions of television viewers and had a major impact on the popularity of the sport. This, along with the innovations introduced by the new <a href="/wiki/American_Football_League" title="American Football League">American Football League</a> (AFL) in the early 1960s, helped football to become the most popular sport in the United States by the mid-1960s.<sup id="cite_ref-Greatest_game_ever_played_29-0" class="reference"><a href="#cite_note-Greatest_game_ever_played-29">[28]</a></sup></p><p>The rival AFL arose in 1960 and challenged the NFL's dominance. The AFL began in relative obscurity but eventually thrived, with an initial television contract with the <a href="/wiki/American_Broadcasting_Company" title="American Broadcasting Company">ABC</a> television network. The AFL's existence forced the conservative NFL to expand to Dallas and Minnesota in an attempt to destroy the new league. Meanwhile, the AFL introduced many new features to professional football in the United States: official time was kept on a scoreboard clock rather than on a watch in the referee's pocket, as the NFL did; optional two-point conversions by pass or run after touchdowns; names on the jerseys of players; and several others, including expansion of the role of minority players, actively recruited by the league in contrast to the NFL. The AFL also signed several star college players who had also been drafted by NFL teams. Competition for players heated up in 1965, when the AFL <a href="/wiki/New_York_Jets" title="New York Jets">New York Jets</a> signed rookie <a href="/wiki/Joe_Namath" title="Joe Namath">Joe Namath</a> to a then-record $437,000 contract (equivalent to $2.71 million in 2018<sup id="cite_ref-inflation-USGDP_30-0" class="reference"><a href="#cite_note-inflation-USGDP-30">[29]</a></sup>). A five-year, $40 million  <a href="/wiki/NBC" title="NBC">NBC</a> television contract followed, which helped to sustain the young league. The bidding war for players ended in 1966 when NFL owners approached the AFL regarding a merger, and the two leagues <a href="/wiki/AFL%E2%80%93NFL_merger" title="AFL–NFL merger">agreed on one</a> that took full effect in 1970. This agreement provided for a common draft that would take place each year, and it instituted an annual World Championship game to be played between the champions of each league. This championship game began play at the end of the 1966 season. Once the merger was completed, it was no longer a championship game between two leagues and reverted to the NFL championship game, which came to be known as the <a href="/wiki/Super_Bowl" title="Super Bowl">Super Bowl</a>.<sup id="cite_ref-The_Second_25_Years_31-0" class="reference"><a href="#cite_note-The_Second_25_Years-31">[30]</a></sup></p><p>College football maintained a tradition of postseason <a href="/wiki/Bowl_games" class="mw-redirect" title="Bowl games">bowl games</a>. Each bowl game was associated with a particular conference and earning a spot in a bowl game was the reward for winning a conference. This arrangement was profitable, but it tended to prevent the two top-ranked teams from meeting in a true national championship game, as they would normally be committed to the bowl games of their respective conferences. Several systems have been used since 1992 to determine a national champion of college football. The first was the <a href="/wiki/Bowl_Coalition" title="Bowl Coalition">Bowl Coalition</a>, in place from 1992 to 1994. This was replaced in 1995 by the <a href="/wiki/Bowl_Alliance" title="Bowl Alliance">Bowl Alliance</a>, which gave way in 1997 to the <a href="/wiki/Bowl_Championship_Series" title="Bowl Championship Series">Bowl Championship Series</a> (BCS).<sup id="cite_ref-BCS_32-0" class="reference"><a href="#cite_note-BCS-32">[31]</a></sup> The BCS arrangement <a href="/wiki/BCS_controversies" class="mw-redirect" title="BCS controversies">proved to be controversial</a>, and was replaced in 2014 by the <a href="/wiki/College_Football_Playoff" title="College Football Playoff">College Football Playoff</a> (CFP).<sup id="cite_ref-Presidents_get_playoff_plan_right_33-0" class="reference"><a href="#cite_note-Presidents_get_playoff_plan_right-33">[32]</a></sup><sup id="cite_ref-34" class="reference"><a href="#cite_note-34">[33]</a></sup></p>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(3)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="Teams_and_positions">Teams and positions</span></h2><section class="mf-section-3 collapsible-block" id="mf-section-3">
<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/American_football_positions" title="American football positions">American football positions</a></div>
<p>A football game is played between two teams of 11 players each.<sup id="cite_ref-NFL_Rules_2012,_p._21_35-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._21-35">[34]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._15_36-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._15-36">[35]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_p._11_37-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_p._11-37">[36]</a></sup> Playing with more on the field is punishable by a penalty.<sup id="cite_ref-NFL_Rules_2012,_p._21_35-1" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._21-35">[34]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._107_38-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._107-38">[37]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_pp._71-72_39-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._71-72-39">[38]</a></sup> Teams may substitute <a href="/wiki/Free_substitution" title="Free substitution">any number of their players</a> between downs;<sup id="cite_ref-NFL_Rules_2012,_pp._21-22_40-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_pp._21-22-40">[39]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_pp._53-54_41-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_pp._53-54-41">[40]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_pp._45-46_42-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._45-46-42">[41]</a></sup> this "platoon" system replaced the original system, which featured limited substitution rules, and has resulted in teams utilizing specialized offensive, defensive and <a href="/wiki/American_football_positions#Special_teams" title="American football positions">special teams</a> units.<sup id="cite_ref-The_innovator_43-0" class="reference"><a href="#cite_note-The_innovator-43">[42]</a></sup></p><p>Individual players in a football game must be designated with a <a href="/wiki/Uniform_number_(American_football)" title="Uniform number (American football)">uniform number</a> between 1 and 99. NFL teams are required to number their players by a league-approved numbering system, and any exceptions must be approved by the <a href="/wiki/Commissioner#Sports" title="Commissioner">Commissioner</a>.<sup id="cite_ref-NFL_Rules_2012,_p._21_35-2" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._21-35">[34]</a></sup> NCAA and NFHS teams are "strongly advised" to number their offensive players according to a league-suggested numbering scheme.<sup id="cite_ref-NCAA_Rules_2011–2012,_pp._21-22_44-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_pp._21-22-44">[43]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_pp._16-17_45-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._16-17-45">[44]</a></sup></p><p>Although the sport is played almost exclusively by men, women are <a href="/wiki/List_of_female_American_football_players" title="List of female American football players">eligible to play</a> in high school, college, and professional football. No woman has ever played in the NFL, but women have played in high school and college football games.<sup id="cite_ref-For_women,_tackling_NFL_is_a_long_shot_46-0" class="reference"><a href="#cite_note-For_women,_tackling_NFL_is_a_long_shot-46">[45]</a></sup> In 2018, 1,100 of the 225,000 players in <a href="/wiki/Pop_Warner_Little_Scholars" title="Pop Warner Little Scholars">Pop Warner Little Scholars</a> youth football were girls, and around 11% of the 5.5 million Americans who report playing tackle football are female according to the Sports and Fitness Industry Association.<sup id="cite_ref-More_Girls_Are_Playing_Football_47-0" class="reference"><a href="#cite_note-More_Girls_Are_Playing_Football-47">[46]</a></sup> Women can also serve as officials; <a href="/wiki/Sarah_Thomas_(American_football_official)" title="Sarah Thomas (American football official)">Sarah Thomas</a> became the NFL's first female official in 2015.<sup id="cite_ref-48" class="reference"><a href="#cite_note-48">[47]</a></sup></p>
<h3 class="in-block"><span class="mw-headline" id="Offensive_unit">Offensive unit</span></h3>
<p>The role of the offensive unit is to advance the football down the field with the ultimate goal of scoring a <a href="/wiki/Touchdown" title="Touchdown">touchdown</a>.<sup id="cite_ref-NFL_in_a_nutshell_49-0" class="reference"><a href="#cite_note-NFL_in_a_nutshell-49">[48]</a></sup></p>
<div class="thumb tleft"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:43BaseDefense.svg" class="image"><noscript><img alt='Diagram showing a green background with a white horizontal line dividing it into two-halves, with eleven small blue squares representing defense players in a formation above the line, and eleven small red circles representing offense players in another formation below the line, with two text captions "Defense" and "Offense", the former placed above the line and the latter below the line' src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e2/43BaseDefense.svg/220px-43BaseDefense.svg.png" decoding="async" width="220" height="147" class="thumbimage" data-file-width="750" data-file-height="500"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 147px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e2/43BaseDefense.svg/220px-43BaseDefense.svg.png" data-alt='Diagram showing a green background with a white horizontal line dividing it into two-halves, with eleven small blue squares representing defense players in a formation above the line, and eleven small red circles representing offense players in another formation below the line, with two text captions "Defense" and "Offense", the former placed above the line and the latter below the line' data-width="220" data-height="147" data-srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e2/43BaseDefense.svg/330px-43BaseDefense.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e2/43BaseDefense.svg/440px-43BaseDefense.svg.png 2x" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:43BaseDefense.svg" class="internal" title="Enlarge"></a></div>A diagram of a typical pre-snap formation. The offense (red) is lined up in a variation of the <a href="/wiki/I_formation" title="I formation">I formation</a>, while the defense (blue) is lined up in the <a href="/wiki/4%E2%80%933_defense" title="4–3 defense">4–3 defense</a>. Both formations are legal</div></div></div>
<p>The offensive team must line up in a legal <a href="/wiki/Formation_(American_football)" title="Formation (American football)">formation</a> before they can snap the ball. An offensive formation is considered illegal if there are more than four players in the <a href="/wiki/Glossary_of_American_football#B" title="Glossary of American football">backfield</a> or fewer than five players numbered 50–79 on the offensive line.<sup id="cite_ref-NCAA_Rules_2011–2012,_p._15_36-1" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._15-36">[35]</a></sup><sup id="cite_ref-NFL_Rules_2012,_pp._21-24_50-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_pp._21-24-50">[49]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_pp._57-58_51-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._57-58-51">[50]</a></sup> Players can line up temporarily in a position whose eligibility is different from what their number permits as long as they report the change immediately to the referee, who then informs the defensive team of the change.<sup id="cite_ref-NFL_Rules_2012,_pp._36,_40_52-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_pp._36,_40-52">[51]</a></sup> Neither team's players, except the <a href="/wiki/Center_(gridiron_football)" title="Center (gridiron football)">center</a> (C), are allowed to line up in or cross the neutral zone until the ball is snapped. Interior offensive linemen are not allowed to move until the snap of the ball.<sup id="cite_ref-Common_Penalties_in_American_Football_53-0" class="reference"><a href="#cite_note-Common_Penalties_in_American_Football-53">[52]</a></sup></p>
<div class="thumb tright"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:Hurricanes_Quarterback.JPG" class="image"><noscript><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c7/Hurricanes_Quarterback.JPG/220px-Hurricanes_Quarterback.JPG" decoding="async" width="220" height="147" class="thumbimage" data-file-width="900" data-file-height="600"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 147px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c7/Hurricanes_Quarterback.JPG/220px-Hurricanes_Quarterback.JPG" data-alt="" data-width="220" data-height="147" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:Hurricanes_Quarterback.JPG" class="internal" title="Enlarge"></a></div>A quarterback for the <a href="/wiki/Kiel_Baltic_Hurricanes" title="Kiel Baltic Hurricanes">Kiel Baltic Hurricanes</a> under center, ready to take the snap</div></div></div>
<p>The main backfield positions are the <a href="/wiki/Quarterback" title="Quarterback">quarterback</a> (QB), <a href="/wiki/Halfback_(American_football)" title="Halfback (American football)">halfback/tailback</a> (HB/TB) and <a href="/wiki/Fullback_(gridiron_football)" title="Fullback (gridiron football)">fullback</a> (FB). The quarterback is the leader of the offense. Either the quarterback or a coach calls the plays. Quarterbacks typically inform the rest of the offense of the play in the <a href="/wiki/Huddle#American_football" title="Huddle">huddle</a> before the team lines up. The quarterback lines up behind the center to take the snap and then hands the ball off, throws it or runs with it.<sup id="cite_ref-NFL_in_a_nutshell_49-1" class="reference"><a href="#cite_note-NFL_in_a_nutshell-49">[48]</a></sup></p><p>The primary role of the halfback, also known as the running back or tailback, is to carry the ball on running plays. Halfbacks may also serve as receivers. Fullbacks tend to be larger than halfbacks and function primarily as blockers, but they are sometimes used as runners in short-yardage situations<sup id="cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-0" class="reference"><a href="#cite_note-Football_Players'_Roles_in_Team_Offense_and_Defense-54">[53]</a></sup> and are seldom used in passing situations.<sup id="cite_ref-Fullbacks_back_en_vogue_55-0" class="reference"><a href="#cite_note-Fullbacks_back_en_vogue-55">[54]</a></sup></p><p>The <a href="/wiki/Lineman_(American_football)#Offensive_line" class="mw-redirect" title="Lineman (American football)">offensive line</a> (OL) consists of several players whose primary function is to <a href="/wiki/Blocking_(American_football)" title="Blocking (American football)">block</a> members of the defensive line from tackling the ball carrier on running plays or <a href="/wiki/Quarterback_sack" title="Quarterback sack">sacking</a> the quarterback on passing plays.<sup id="cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-1" class="reference"><a href="#cite_note-Football_Players'_Roles_in_Team_Offense_and_Defense-54">[53]</a></sup> The leader of the offensive line is the center, who is responsible for snapping the ball to the quarterback, blocking,<sup id="cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-2" class="reference"><a href="#cite_note-Football_Players'_Roles_in_Team_Offense_and_Defense-54">[53]</a></sup> and for making sure that the other linemen do their jobs during the play.<sup id="cite_ref-Centers:_The_Unsung_Heroes_of_Football_56-0" class="reference"><a href="#cite_note-Centers:_The_Unsung_Heroes_of_Football-56">[55]</a></sup> On either side of the center are the <a href="/wiki/Guard_(American_and_Canadian_football)" class="mw-redirect" title="Guard (American and Canadian football)">guards</a> (G), while <a href="/wiki/Tackle_(American_and_Canadian_football)#Offensive_tackle" class="mw-redirect" title="Tackle (American and Canadian football)">tackles</a> (T) line up outside the guards.
</p><p>The principal receivers are the <a href="/wiki/Wide_receiver" title="Wide receiver">wide receivers</a> (WR) and the <a href="/wiki/Tight_end" title="Tight end">tight ends</a> (TE).<sup id="cite_ref-Football's_Offensive_Team:_The_Receivers_57-0" class="reference"><a href="#cite_note-Football's_Offensive_Team:_The_Receivers-57">[56]</a></sup> Wide receivers line up on or near the line of scrimmage, split outside the line. The main goal of the wide receiver is to catch passes thrown by the quarterback,<sup id="cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-3" class="reference"><a href="#cite_note-Football_Players'_Roles_in_Team_Offense_and_Defense-54">[53]</a></sup> but they may also function as decoys or as blockers during running plays. Tight ends line up outside the tackles and function both as receivers and as blockers.<sup id="cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-4" class="reference"><a href="#cite_note-Football_Players'_Roles_in_Team_Offense_and_Defense-54">[53]</a></sup></p>
<h3 class="in-block"><span class="mw-headline" id="Defensive_unit">Defensive unit</span></h3>
<div class="thumb tright"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:Arian_Foster_fumble.jpg" class="image"><noscript><img alt="Photograph of defensive players tackling an offensive player who has just lost control of the football" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/74/Arian_Foster_fumble.jpg/220px-Arian_Foster_fumble.jpg" decoding="async" width="220" height="147" class="thumbimage" data-file-width="2029" data-file-height="1353"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 147px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/7/74/Arian_Foster_fumble.jpg/220px-Arian_Foster_fumble.jpg" data-alt="Photograph of defensive players tackling an offensive player who has just lost control of the football" data-width="220" data-height="147" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:Arian_Foster_fumble.jpg" class="internal" title="Enlarge"></a></div><a href="/wiki/Dallas_Cowboys" title="Dallas Cowboys">Dallas Cowboys</a> defensive players force <a href="/wiki/Houston_Texans" title="Houston Texans">Houston Texans</a> running back <a href="/wiki/Arian_Foster" title="Arian Foster">Arian Foster</a> to fumble the ball</div></div></div>
<p>The role of the defense is to prevent the offense from scoring by <a href="/wiki/Tackle_(football_move)#American_and_Canadian_football" title="Tackle (football move)">tackling</a> the ball carrier or by forcing <a href="/wiki/Turnover_(gridiron_football)" title="Turnover (gridiron football)">turnovers</a> (<a href="/wiki/Interception" title="Interception">interceptions</a> or <a href="/wiki/Fumble" title="Fumble">fumbles</a>).<sup id="cite_ref-NFL_in_a_nutshell_49-2" class="reference"><a href="#cite_note-NFL_in_a_nutshell-49">[48]</a></sup></p><p>The <a href="/wiki/Lineman_(American_football)#Defensive_line" class="mw-redirect" title="Lineman (American football)">defensive line</a> (DL) consists of <a href="/wiki/Defensive_end" title="Defensive end">defensive ends</a> (DE) and <a href="/wiki/Tackle_(American_and_Canadian_football)#Defensive_tackle" class="mw-redirect" title="Tackle (American and Canadian football)">defensive tackles</a> (DT). Defensive ends line up on the ends of the line, while defensive tackles line up inside, between the defensive ends. The primary responsibilities of defensive ends and defensive tackles are to stop running plays on the outside and inside, respectively, to pressure the quarterback on passing plays, and to occupy the line so that the <a href="/wiki/Linebacker" title="Linebacker">linebackers</a> can break through.<sup id="cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-5" class="reference"><a href="#cite_note-Football_Players'_Roles_in_Team_Offense_and_Defense-54">[53]</a></sup></p>
<div class="thumb tleft"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:Brent_Grimes-Hamburg_Sea_Devils.jpg" class="image"><noscript><img alt="A defensive player leaps into the air in front of a receiver and intercepts the pass" src="//upload.wikimedia.org/wikipedia/commons/thumb/1/15/Brent_Grimes-Hamburg_Sea_Devils.jpg/220px-Brent_Grimes-Hamburg_Sea_Devils.jpg" decoding="async" width="220" height="146" class="thumbimage" data-file-width="1600" data-file-height="1065"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 146px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/1/15/Brent_Grimes-Hamburg_Sea_Devils.jpg/220px-Brent_Grimes-Hamburg_Sea_Devils.jpg" data-alt="A defensive player leaps into the air in front of a receiver and intercepts the pass" data-width="220" data-height="146" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:Brent_Grimes-Hamburg_Sea_Devils.jpg" class="internal" title="Enlarge"></a></div>Cornerback <a href="/wiki/Brent_Grimes" title="Brent Grimes">Brent Grimes</a> of the <a href="/wiki/Hamburg_Sea_Devils" title="Hamburg Sea Devils">Hamburg Sea Devils</a> intercepts a pass</div></div></div>
<p>Linebackers line up behind the defensive line but in front of the defensive backfield. They are divided into two types: middle linebackers (MLB) and outside linebackers (OLB). Linebackers are the defensive leaders and call the defensive plays. Their diverse roles include defending the run, pressuring the quarterback, and guarding backs, wide receivers and tight ends in the passing game.<sup id="cite_ref-Football's_Defensive_Team:_The_Linebackers_58-0" class="reference"><a href="#cite_note-Football's_Defensive_Team:_The_Linebackers-58">[57]</a></sup></p><p>The <a href="/wiki/Defensive_back" title="Defensive back">defensive backfield</a>, often called the secondary, consists of <a href="/wiki/Cornerback" title="Cornerback">cornerbacks</a> (CB) and <a href="/wiki/Safety_(gridiron_football_position)" title="Safety (gridiron football position)">safeties</a> (S). Safeties are themselves divided into free safeties (FS) and strong safeties (SS).<sup id="cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-6" class="reference"><a href="#cite_note-Football_Players'_Roles_in_Team_Offense_and_Defense-54">[53]</a></sup> Cornerbacks line up outside the defensive formation, typically opposite a receiver to be able to cover them. Safeties line up between the cornerbacks but farther back in the secondary. Safeties are the last line of defense and are responsible for stopping deep passing plays as well as running plays.<sup id="cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-7" class="reference"><a href="#cite_note-Football_Players'_Roles_in_Team_Offense_and_Defense-54">[53]</a></sup></p>
<div style="clear:both;"></div>
<h3 class="in-block"><span class="mw-headline" id="Special_teams_unit">Special teams unit</span></h3>
<div class="thumb tright"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:Jeff_Reed_kickoff_2006.jpg" class="image"><noscript><img alt="Four players run up the field as the kicker executes a kickoff" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/36/Jeff_Reed_kickoff_2006.jpg/220px-Jeff_Reed_kickoff_2006.jpg" decoding="async" width="220" height="147" class="thumbimage" data-file-width="1024" data-file-height="683"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 147px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/3/36/Jeff_Reed_kickoff_2006.jpg/220px-Jeff_Reed_kickoff_2006.jpg" data-alt="Four players run up the field as the kicker executes a kickoff" data-width="220" data-height="147" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:Jeff_Reed_kickoff_2006.jpg" class="internal" title="Enlarge"></a></div>Kicker <a href="/wiki/Jeff_Reed_(American_football)" title="Jeff Reed (American football)">Jeff Reed</a> of the <a href="/wiki/Pittsburgh_Steelers" title="Pittsburgh Steelers">Pittsburgh Steelers</a> executes a kickoff</div></div></div>
<p>The special teams unit is responsible for all kicking plays. The special teams unit of the team in control of the ball tries to execute field goal (FG) attempts, <a href="/wiki/Punt_(gridiron_football)" title="Punt (gridiron football)">punts</a> and <a href="/wiki/Kickoff_(gridiron_football)" title="Kickoff (gridiron football)">kickoffs</a>, while the opposing team's unit will aim to block or return them.<sup id="cite_ref-NFL_in_a_nutshell_49-3" class="reference"><a href="#cite_note-NFL_in_a_nutshell-49">[48]</a></sup></p><p>Three positions are specific to the field goal and PAT (point-after-touchdown) unit: the <a href="/wiki/Placekicker" title="Placekicker">placekicker</a> (K or PK), <a href="/wiki/Holder_(American_football)" class="mw-redirect" title="Holder (American football)">holder</a> (H) and <a href="/wiki/Long_snapper" title="Long snapper">long snapper</a> (LS). The long snapper's job is to snap the football to the holder, who will catch and position it for the placekicker. There is not usually a holder on kickoffs, because the ball is kicked off a tee; however, a holder may be used in certain situations, such as if wind is preventing the ball from remaining upright on the tee. The player on the receiving team who catches the ball is known as the <a href="/wiki/Kickoff_returner" class="mw-redirect" title="Kickoff returner">kickoff returner</a> (KR).<sup id="cite_ref-The_Role_of_Special_Teams_in_a_Football_Game_59-0" class="reference"><a href="#cite_note-The_Role_of_Special_Teams_in_a_Football_Game-59">[58]</a></sup></p><p>The positions specific to punt plays are the <a href="/wiki/Punter_(football)" title="Punter (football)">punter</a> (P), long snapper, <a href="/wiki/Upback" title="Upback">upback</a> and <a href="/wiki/Gunner_(American_football)" title="Gunner (American football)">gunner</a>. The long snapper snaps the football directly to the punter, who then drops and kicks it before it hits the ground. Gunners line up split outside the line and race down the field, aiming to tackle the <a href="/wiki/Punt_returner" class="mw-redirect" title="Punt returner">punt returner</a> (PR)—the player who catches the punt. Upbacks line up a short distance behind the line of scrimmage, providing additional protection to the punter.<sup id="cite_ref-Football_Special_Teams:_Players_on_a_Punt_Team_60-0" class="reference"><a href="#cite_note-Football_Special_Teams:_Players_on_a_Punt_Team-60">[59]</a></sup></p>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(4)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="Rules">Rules</span></h2><section class="mf-section-4 collapsible-block" id="mf-section-4">
<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/American_football_rules" title="American football rules">American football rules</a></div>
<h3 class="in-block"><span class="mw-headline" id="Scoring">Scoring</span></h3>
<div class="thumb tright"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:2006_Navy_-_Tusla.jpg" class="image"><noscript><img alt="A player pursued by an opponent dives into the end zone in front of an official to score a touchdown." src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d8/2006_Navy_-_Tusla.jpg/220px-2006_Navy_-_Tusla.jpg" decoding="async" width="220" height="143" class="thumbimage" data-file-width="3008" data-file-height="1960"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 143px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d8/2006_Navy_-_Tusla.jpg/220px-2006_Navy_-_Tusla.jpg" data-alt="A player pursued by an opponent dives into the end zone in front of an official to score a touchdown." data-width="220" data-height="143" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:2006_Navy_-_Tusla.jpg" class="internal" title="Enlarge"></a></div>A player for the <a href="/wiki/Navy_Midshipmen_football" title="Navy Midshipmen football">Navy Midshipmen</a> (dark jersey) scores a touchdown while a defender from the <a href="/wiki/Tulsa_Golden_Hurricane_football" title="Tulsa Golden Hurricane football">Tulsa Golden Hurricane</a> (in white) looks on. The goal line is marked by the small orange pylon</div></div></div>
<p>In football, the winner is the team that has scored more points at the end of the game. There are multiple ways to score in a football game. The touchdown (TD), worth six points, is the most valuable scoring play in American football. A touchdown is scored when a live ball is advanced into, caught in, or recovered in the opposing team's end zone.<sup id="cite_ref-NFL_in_a_nutshell_49-4" class="reference"><a href="#cite_note-NFL_in_a_nutshell-49">[48]</a></sup> The scoring team then attempts a try or conversion, more commonly known as the point(s)-after-touchdown (PAT), which is a single scoring opportunity. A PAT is most commonly attempted from the two- or three-yard line, depending on the level of play. If a PAT is scored by a placekick or dropkick through the goal posts, it is worth one point, typically called the extra point. If it is scored by what would normally be a touchdown it is worth two points, typically called the <a href="/wiki/Two-point_conversion" title="Two-point conversion">two-point conversion</a>. In general, the extra point is almost always successful while the two-point conversion is a much riskier play with a higher probability of failure; accordingly, extra point attempts are far more common than two-point conversion attempts.<sup id="cite_ref-Duke_61-0" class="reference"><a href="#cite_note-Duke-61">[60]</a></sup></p><p>A field goal (FG), worth three points, is scored when the ball is placekicked or dropkicked through the uprights and over the crossbars of the defense's goalposts.<sup id="cite_ref-NFL_Rules_2012,_p._57-59_62-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._57-59-62">[61]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._79-80_63-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._79-80-63">[62]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_p._66_64-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_p._66-64">[63]</a></sup> After a PAT attempt or successful field goal, the scoring team must kick the ball off to the other team.<sup id="cite_ref-Beginner's_Guide_to_Football_65-0" class="reference"><a href="#cite_note-Beginner's_Guide_to_Football-65">[64]</a></sup></p><p>A <a href="/wiki/Safety_(gridiron_football_score)" title="Safety (gridiron football score)">safety</a> is scored when the ball carrier is tackled in their own end zone. Safeties are worth two points, which are awarded to the defense.<sup id="cite_ref-NFL_in_a_nutshell_49-5" class="reference"><a href="#cite_note-NFL_in_a_nutshell-49">[48]</a></sup> In addition, the team that conceded the safety must kick the ball to the scoring team via a <a href="/wiki/Safety_kick#Resuming_play_after_a_safety" class="mw-redirect" title="Safety kick">free kick</a>.<sup id="cite_ref-NFL_Rules_2012,_p._60_66-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._60-66">[65]</a></sup></p>
<h3 class="in-block"><span class="mw-headline" id="Field_and_equipment">Field and equipment</span></h3>
<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/American_football_field" title="American football field">American football field</a></div>
<div class="thumb tleft"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:Edward_Jones_Dome_endzone_view.jpg" class="image"><noscript><img alt="Photograph of a football field taken from the end zone showing goal posts in the foreground" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Edward_Jones_Dome_endzone_view.jpg/220px-Edward_Jones_Dome_endzone_view.jpg" decoding="async" width="220" height="132" class="thumbimage" data-file-width="3264" data-file-height="1952"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 132px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Edward_Jones_Dome_endzone_view.jpg/220px-Edward_Jones_Dome_endzone_view.jpg" data-alt="Photograph of a football field taken from the end zone showing goal posts in the foreground" data-width="220" data-height="132" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:Edward_Jones_Dome_endzone_view.jpg" class="internal" title="Enlarge"></a></div>A football field as seen from behind one end zone. The tall, yellow goal posts mark where the ball must pass for a successful field goal or extra point. The large, rectangular area marked with the team name is the end zone</div></div></div>
<p>Football games are played on a rectangular <a href="/wiki/American_football_field" title="American football field">field</a> that measures 120 yards (110 m) long and <span class="frac nowrap">53<span class="visualhide"> </span><sup>1</sup>⁄<sub>3</sub></span> yards (48.8 m) wide. Lines marked along the ends and sides of the field are known as the end lines and <a href="/wiki/Sidelines" title="Sidelines">sidelines</a>. <a href="/wiki/Goal_line_(American_football)" class="mw-redirect" title="Goal line (American football)">Goal lines</a> are marked 10 yards (9.1 m) inward from each end line.<sup id="cite_ref-NFL_Rules_2012,_p._v,_1_67-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._v,_1-67">[66]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_pp._18-19,_23–24_68-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_pp._18-19,_23%E2%80%9324-68">[67]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_pp._11-12,_13,_28_69-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._11-12,_13,_28-69">[68]</a></sup></p><p>Weighted pylons are placed the sidelines on the inside corner of the intersections with the goal lines and end lines. White markings on the field identify the distance from the end zone. Inbound lines, or <a href="/wiki/Hash_marks" class="mw-redirect" title="Hash marks">hash marks</a>, are short parallel lines that mark off 1-yard (0.91 m) increments. <a href="/wiki/Yard_lines" class="mw-redirect" title="Yard lines">Yard lines</a>, which can run the width of the field, are marked every 5 yards (4.6 m). A one-yard-wide line is placed at each end of the field; this line is marked at the center of the two-yard line in professional play and at the three-yard line in college play. Numerals that display the distance from the closest goal line in yards are placed on both sides of the field every ten yards.<sup id="cite_ref-NFL_Rules_2012,_p._v,_1_67-1" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._v,_1-67">[66]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_pp._18-19,_23–24_68-1" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_pp._18-19,_23%E2%80%9324-68">[67]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_pp._11-12,_13,_28_69-1" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._11-12,_13,_28-69">[68]</a></sup></p><p><a href="/wiki/Goalposts" class="mw-redirect" title="Goalposts">Goalposts</a> are located at the center of the plane of the two end lines. The crossbar of these posts is 10 feet (3.0 m) above the ground, with vertical uprights at the end of the crossbar 18 feet 6 inches (5.64 m) apart for professional and collegiate play, and 23 feet 4 inches (7.11 m) apart for high school play.<sup id="cite_ref-NFL_Rules_2012,_p._2_70-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._2-70">[69]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._18_71-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._18-71">[70]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_p._14-15_72-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_p._14-15-72">[71]</a></sup> The uprights extend vertically 35 feet (11 m) on professional fields, a minimum of 10 yards (9.1 m) on college fields, and a minimum of 10 feet (3.0 m) on high school fields. Goal posts are padded at the base, and orange ribbons are normally placed at the tip of each upright as indicators of wind strength and direction.<sup id="cite_ref-NFL_Rules_2012,_p._2_70-1" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._2-70">[69]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._18_71-1" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._18-71">[70]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_p._14-15_72-1" class="reference"><a href="#cite_note-NFHS_Rules_2012,_p._14-15-72">[71]</a></sup></p><p>The <a href="/wiki/Ball_(gridiron_football)" title="Ball (gridiron football)">football</a> itself is an oval ball, similar to the balls used in rugby or <a href="/wiki/Australian_rules_football" title="Australian rules football">Australian rules football</a>.<sup id="cite_ref-Bounce_of_an_oval_shaped_football_73-0" class="reference"><a href="#cite_note-Bounce_of_an_oval_shaped_football-73">[72]</a></sup> At all levels of play, the football is inflated to <span class="frac nowrap">12<span class="visualhide"> </span><sup>1</sup>⁄<sub>2</sub></span> to <span class="frac nowrap">13<span class="visualhide"> </span><sup>1</sup>⁄<sub>2</sub></span> pounds per square inch (86 to 93 kPa) and weighs 14 to 15 ounces (400 to 430 g);<sup id="cite_ref-NFHS_Rules_2012,_p._14-15_72-2" class="reference"><a href="#cite_note-NFHS_Rules_2012,_p._14-15-72">[71]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._20_74-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._20-74">[73]</a></sup><sup id="cite_ref-NFL_Rules_2012,_p._3_75-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._3-75">[74]</a></sup> beyond that, the exact dimensions vary slightly. In professional play the ball has a long axis of 11 to <span class="frac nowrap">11<span class="visualhide"> </span><sup>1</sup>⁄<sub>4</sub></span> inches (28 to 29 cm), a long circumference of 28 to <span class="frac nowrap">28<span class="visualhide"> </span><sup>1</sup>⁄<sub>2</sub></span> inches (71 to 72 cm), and a short circumference of 21 to <span class="frac nowrap">21<span class="visualhide"> </span><sup>1</sup>⁄<sub>4</sub></span> inches (53 to 54 cm).<sup id="cite_ref-76" class="reference"><a href="#cite_note-76">[75]</a></sup> In college and high school play the ball has a long axis of <span class="frac nowrap">10<span class="visualhide"> </span><sup>7</sup>⁄<sub>8</sub></span> to <span class="frac nowrap">11<span class="visualhide"> </span><sup>7</sup>⁄<sub>16</sub></span> inches (27.6 to 29.1 cm), a long circumference of <span class="frac nowrap">27<span class="visualhide"> </span><sup>3</sup>⁄<sub>4</sub></span> to <span class="frac nowrap">28<span class="visualhide"> </span><sup>1</sup>⁄<sub>2</sub></span> inches (70 to 72 cm), and a short circumference of <span class="frac nowrap">20<span class="visualhide"> </span><sup>3</sup>⁄<sub>4</sub></span> to <span class="frac nowrap">21<span class="visualhide"> </span><sup>1</sup>⁄<sub>4</sub></span> inches (53 to 54 cm).<sup id="cite_ref-NFHS_Rules_2012,_p._14-15_72-3" class="reference"><a href="#cite_note-NFHS_Rules_2012,_p._14-15-72">[71]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._20_74-1" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._20-74">[73]</a></sup></p>
<h3 class="in-block"><span class="mw-headline" id="Duration_and_time_stoppages">Duration and time stoppages</span></h3>
<p>Football games last for a total of 60 minutes in professional and college play and are divided into two halves of 30 minutes and four quarters of 15 minutes.<sup id="cite_ref-NFL_Rules_2012,_p._14_77-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._14-77">[76]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._45_78-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._45-78">[77]</a></sup> High school football games are 48 minutes in length with two halves of 24 minutes and four quarters of 12 minutes.<sup id="cite_ref-NFHS_Rules_2012,_pp._38-39_79-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._38-39-79">[78]</a></sup> The two halves are separated by a <a href="/wiki/Half-time" title="Half-time">halftime</a> period, and the first and third quarters are followed by a short break.<sup id="cite_ref-NFL_Rules_2012,_p._14_77-1" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._14-77">[76]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._45_78-1" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._45-78">[77]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_p._39_80-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_p._39-80">[79]</a></sup> Before the game starts, the referee and each team's <a href="/wiki/Captain_(sports)" title="Captain (sports)">captain</a> meet at midfield for a <a href="/wiki/Coin_toss" class="mw-redirect" title="Coin toss">coin toss</a>. The visiting team can call either "heads" or "tails"; the winner of the toss chooses whether to receive or kick off the ball or which goal they wish to defend. They can defer their choice until the second half. Unless the winning team decides to defer, the losing team chooses the option the winning team did not select—to receive, kick, or select a goal to defend to begin the second half. Most teams choose to receive or defer, because choosing to kick the ball to start the game allows the other team to choose which goal to defend.<sup id="cite_ref-TMQ's_all-haiku_NFL_preview_81-0" class="reference"><a href="#cite_note-TMQ's_all-haiku_NFL_preview-81">[80]</a></sup> Teams switch goals following the first and third quarters.<sup id="cite_ref-How_Football_Game_Time_Is_Measured_in_Quarters_82-0" class="reference"><a href="#cite_note-How_Football_Game_Time_Is_Measured_in_Quarters-82">[81]</a></sup> If a down is in progress when a quarter ends, play continues until the down is completed.<sup id="cite_ref-NFL_Rules_2012,_p._14-18_83-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._14-18-83">[82]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_pp._47-53_84-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_pp._47-53-84">[83]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_pp._38-45_85-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._38-45-85">[84]</a></sup></p><p>Games last longer than their defined length due to play stoppages—the average NFL game lasts slightly over three hours.<sup id="cite_ref-USA_Today_86-0" class="reference"><a href="#cite_note-USA_Today-86">[85]</a></sup> Time in a football game is measured by the game clock. An operator is responsible for starting, stopping and operating the game clock based on the direction of the appropriate <a href="/wiki/Official_(American_football)" class="mw-redirect" title="Official (American football)">official</a>.<sup id="cite_ref-NFL_Rules_2012,_p._14_77-2" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._14-77">[76]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_pp._16,_41_87-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_pp._16,_41-87">[86]</a></sup> A separate <a href="/wiki/Play_clock" title="Play clock">play clock</a> is used to determine if a <a href="/wiki/Delay_of_game#American_football" title="Delay of game">delay of game</a> infraction has been committed. If the play clock expires before the ball has been snapped or free-kicked, a delay of game foul is called on the offense. The play clock is set 25 seconds after certain administrative stoppages in play and to 40 seconds when play is proceeding without such stoppages.<sup id="cite_ref-NFL_Rules_2012,_p._14-18_83-1" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._14-18-83">[82]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_pp._41,_46–47_88-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_pp._41,_46%E2%80%9347-88">[87]</a></sup><sup id="cite_ref-NFHS_Rules_2019_89-0" class="reference"><a href="#cite_note-NFHS_Rules_2019-89">[88]</a></sup></p>
<h3 class="in-block"><span class="mw-headline" id="Advancing_the_ball_and_downs">Advancing the ball and downs</span></h3>
<div class="thumb tleft"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:Delhomme_goes_deep.jpg" class="image"><noscript><img alt="A quarterback is shown in the process of throwing a forward pass. His offensive linemen are in front of him." src="//upload.wikimedia.org/wikipedia/commons/thumb/0/00/Delhomme_goes_deep.jpg/220px-Delhomme_goes_deep.jpg" decoding="async" width="220" height="124" class="thumbimage" data-file-width="1548" data-file-height="871"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 124px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/0/00/Delhomme_goes_deep.jpg/220px-Delhomme_goes_deep.jpg" data-alt="A quarterback is shown in the process of throwing a forward pass. His offensive linemen are in front of him." data-width="220" data-height="124" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:Delhomme_goes_deep.jpg" class="internal" title="Enlarge"></a></div><a href="/wiki/Carolina_Panthers" title="Carolina Panthers">Carolina Panthers</a> quarterback <a href="/wiki/Jake_Delhomme" title="Jake Delhomme">Jake Delhomme</a> (number 17) in the motion of throwing a forward pass</div></div></div>
<p>There are two main ways the offense can advance the ball: <a href="/wiki/Rush_(gridiron_football)" title="Rush (gridiron football)">running</a> and <a href="/wiki/Forward_pass#American_and_Canadian_football" title="Forward pass">passing</a>. In a typical play, the center passes the ball backwards and between their legs to the quarterback in a process known as the <a href="/wiki/Snap_(American_and_Canadian_football)" class="mw-redirect" title="Snap (American and Canadian football)">snap</a>. The quarterback then either hands the ball off to a back, throws the ball, or runs with it. The play ends when the player with the ball is tackled or goes out-of-bounds or a pass hits the ground without a player having caught it. A forward pass can be legally attempted only if the passer is behind the line of scrimmage; only one forward pass can be attempted per down.<sup id="cite_ref-Beginner's_Guide_to_Football_65-1" class="reference"><a href="#cite_note-Beginner's_Guide_to_Football-65">[64]</a></sup> Like in rugby, players can also <a href="/wiki/Lateral_pass" title="Lateral pass">pass the ball backwards</a> at any point during a play.<sup id="cite_ref-90" class="reference"><a href="#cite_note-90">[89]</a></sup> In the NFL, a down also ends immediately if the runner's helmet comes off.<sup id="cite_ref-When_a_runner's_helmet_comes_off,_he's_down_91-0" class="reference"><a href="#cite_note-When_a_runner's_helmet_comes_off,_he's_down-91">[90]</a></sup></p><p>The offense is given a series of four plays, known as <a href="/wiki/Down_(American_and_Canadian_football)" class="mw-redirect" title="Down (American and Canadian football)">downs</a>. If the offense advances ten or more yards in the four downs, they are awarded a new set of four downs. If they fail to advance ten yards, possession of the football is turned over to the defense. In most situations, if the offense reaches their fourth down they will <a href="/wiki/Punt_(American_football)" class="mw-redirect" title="Punt (American football)">punt</a> the ball to the other team, which forces them to begin their drive from farther down the field; if they are in <a href="/wiki/Field_goal_range" title="Field goal range">field goal range</a>, they might attempt to score a field goal instead.<sup id="cite_ref-Beginner's_Guide_to_Football_65-2" class="reference"><a href="#cite_note-Beginner's_Guide_to_Football-65">[64]</a></sup> A group of officials, the chain crew, keeps track of both the downs and the distance measurements.<sup id="cite_ref-The_Orchestration_of_the_Chain_Gang_92-0" class="reference"><a href="#cite_note-The_Orchestration_of_the_Chain_Gang-92">[91]</a></sup> On television, a yellow line is electronically superimposed on the field to show the first down line to the viewing audience.<sup id="cite_ref-Yellow_line_93-0" class="reference"><a href="#cite_note-Yellow_line-93">[92]</a></sup></p>
<h3 class="in-block"><span class="mw-headline" id="Kicking">Kicking</span></h3>
<div class="thumb tright"><div class="thumbinner" style="width:172px;"><a href="/wiki/File:MasonCrosbyFG-Edit.jpg" class="image"><noscript><img alt="A placekicker attempts a field goal by kicking the ball from the hands of a holder." src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/MasonCrosbyFG-Edit.jpg/170px-MasonCrosbyFG-Edit.jpg" decoding="async" width="170" height="196" class="thumbimage" data-file-width="1701" data-file-height="1960"></noscript><span class="lazy-image-placeholder" style="width: 170px;height: 196px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/MasonCrosbyFG-Edit.jpg/170px-MasonCrosbyFG-Edit.jpg" data-alt="A placekicker attempts a field goal by kicking the ball from the hands of a holder." data-width="170" data-height="196" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:MasonCrosbyFG-Edit.jpg" class="internal" title="Enlarge"></a></div><a href="/wiki/Green_Bay_Packers" title="Green Bay Packers">Green Bay Packers</a> placekicker <a href="/wiki/Mason_Crosby" title="Mason Crosby">Mason Crosby</a> attempts a field goal by kicking the ball from the hands of a holder. This is the standard method to score field goals or extra points.<sup id="cite_ref-PFRA_94-0" class="reference"><a href="#cite_note-PFRA-94">[93]</a></sup><sup id="cite_ref-The_last_dropkick_95-0" class="reference"><a href="#cite_note-The_last_dropkick-95">[94]</a></sup></div></div></div>
<p>There are two categories of kicks in football: scrimmage kicks, which can be executed by the offensive team on any down from behind or on the line of scrimmage,<sup id="cite_ref-NFL_Rules_2012,_p._50_96-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._50-96">[95]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._34_97-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._34-97">[96]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_p._32_98-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_p._32-98">[97]</a></sup> and free kicks.<sup id="cite_ref-NFL_Rules_2012,_p._6_99-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._6-99">[98]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._30_100-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._30-100">[99]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_p._27_101-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_p._27-101">[100]</a></sup> The free kicks are the <a href="/wiki/Kickoff_(American_football)" class="mw-redirect" title="Kickoff (American football)">kickoff</a>, which starts the first and third quarters and overtime and follows a try attempt or a successful field goal; the safety kick follows a safety.<sup id="cite_ref-NCAA_Rules_2011–2012,_p._34_97-1" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._34-97">[96]</a></sup><sup id="cite_ref-NFL_Rules_2012,_pp._8-9_102-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_pp._8-9-102">[101]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_pp._31-32_103-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._31-32-103">[102]</a></sup></p><p>On a kickoff, the ball is placed at the 35-yard line of the kicking team in professional and college play and at the 40-yard line in high school play. The ball may be drop-kicked or place-kicked. If a place kick is chosen, the ball can be placed on the ground or a tee; a holder may be used in either case. On a safety kick, the kicking team kicks the ball from their own 20-yard line. They can punt, drop-kick or place-kick the ball, but a tee may not be used in professional play. Any member of the receiving team may catch or advance the ball. The ball may be recovered by the kicking team once it has gone at least ten yards and has touched the ground or has been touched by any member of the receiving team.<sup id="cite_ref-NFL_Rules_2012,_pp._29-30_104-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_pp._29-30-104">[103]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_pp._61-64_105-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_pp._61-64-105">[104]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_pp._15,_46,_52–53_106-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._15,_46,_52%E2%80%9353-106">[105]</a></sup></p><p>The three types of scrimmage kicks are place kicks, drop kicks, and punts. Only place kicks and drop kicks can score points.<sup id="cite_ref-NFL_Rules_2012,_p._57-59_62-1" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._57-59-62">[61]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_p._79-80_63-1" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_p._79-80-63">[62]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_p._66_64-1" class="reference"><a href="#cite_note-NFHS_Rules_2012,_p._66-64">[63]</a></sup> The place kick is the standard method used to score points,<sup id="cite_ref-PFRA_94-1" class="reference"><a href="#cite_note-PFRA-94">[93]</a></sup> because the pointy shape of the football makes it difficult to reliably drop kick.<sup id="cite_ref-PFRA_94-2" class="reference"><a href="#cite_note-PFRA-94">[93]</a></sup><sup id="cite_ref-The_last_dropkick_95-1" class="reference"><a href="#cite_note-The_last_dropkick-95">[94]</a></sup> Once the ball has been kicked from a scrimmage kick, it can be advanced by the kicking team only if it is caught or recovered behind the line of scrimmage. If it is touched or recovered by the kicking team beyond this line, it becomes dead at the spot where it was touched.<sup id="cite_ref-NFL_Rules_2012,_pp._33-34,_50–53_107-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_pp._33-34,_50%E2%80%9353-107">[106]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_pp._55-56,_63–64_108-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_pp._55-56,_63%E2%80%9364-108">[107]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_pp._49,_53–54_109-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._49,_53%E2%80%9354-109">[108]</a></sup> The kicking team is prohibited from interfering with the receiver's opportunity to catch the ball. The receiving team has the option of signaling for a <a href="/wiki/Fair_catch" title="Fair catch">fair catch</a>, which prohibits the defense from blocking into or tackling the receiver. The play ends as soon as the ball is caught and the ball may not be advanced.<sup id="cite_ref-NFL_Rules_2012,_p._7_110-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_p._7-110">[109]</a></sup><sup id="cite_ref-NCAA_Rules_2011–2012,_pp._30,_66–67_111-0" class="reference"><a href="#cite_note-NCAA_Rules_2011%E2%80%932012,_pp._30,_66%E2%80%9367-111">[110]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_p._2756,_112-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_p._2756,-112">[111]</a></sup></p>
<h3 class="in-block"><span class="mw-headline" id="Officials_and_fouls">Officials and fouls</span></h3>
<div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Official_(American_football)" class="mw-redirect" title="Official (American football)">Official (American football)</a>, <a href="/wiki/Chain_crew" title="Chain crew">Chain crew</a>, and <a href="/wiki/Penalty_(gridiron_football)" title="Penalty (gridiron football)">Penalty (gridiron football)</a></div>
<div class="thumb tright"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:American_football_referees.jpg" class="image"><noscript><img alt="Seven officials are pictured meeting at the infield. Officials meeting at midfield" src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fe/American_football_referees.jpg/220px-American_football_referees.jpg" decoding="async" width="220" height="220" class="thumbimage" data-file-width="2108" data-file-height="2108"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 220px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fe/American_football_referees.jpg/220px-American_football_referees.jpg" data-alt="Seven officials are pictured meeting at the infield. Officials meeting at midfield" data-width="220" data-height="220" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:American_football_referees.jpg" class="internal" title="Enlarge"></a></div></div></div></div>
<div class="thumb tright"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:First_down_measurement_at_EWU_at_Cal_2009-09-12.JPG" class="image"><noscript><img alt="Officials are using a chain to measure for a first down." src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3f/First_down_measurement_at_EWU_at_Cal_2009-09-12.JPG/220px-First_down_measurement_at_EWU_at_Cal_2009-09-12.JPG" decoding="async" width="220" height="165" class="thumbimage" data-file-width="2288" data-file-height="1712"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 165px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3f/First_down_measurement_at_EWU_at_Cal_2009-09-12.JPG/220px-First_down_measurement_at_EWU_at_Cal_2009-09-12.JPG" data-alt="Officials are using a chain to measure for a first down." data-width="220" data-height="165" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:First_down_measurement_at_EWU_at_Cal_2009-09-12.JPG" class="internal" title="Enlarge"></a></div>Officials use the chains to measure for a first down. Here, the ball is just short of the pole and therefore short of a first down.</div></div></div>
<p>Officials are responsible for enforcing game rules and monitoring the clock. All officials carry a <a href="/wiki/Whistle" title="Whistle">whistle</a> and wear black-and-white striped shirts and black hats except for the referee, whose hat is white. Each carries a <a href="/wiki/Penalty_flag" title="Penalty flag">weighted yellow flag</a> that is thrown to the ground to signal that a <a href="/wiki/Penalty_(gridiron_football)" title="Penalty (gridiron football)">foul</a> has been called. An official who spots multiple fouls will throw their hat as a secondary signal.<sup id="cite_ref-American_Football_Officials_113-0" class="reference"><a href="#cite_note-American_Football_Officials-113">[112]</a></sup> The seven officials (of a standard seven-man crew; lower levels of play up to the college level use fewer officials) on the field are each tasked with a different set of responsibilities:<sup id="cite_ref-American_Football_Officials_113-1" class="reference"><a href="#cite_note-American_Football_Officials-113">[112]</a></sup></p>
<ul><li>The <b>referee</b> is positioned behind and to the side of the offensive backs. The referee is charged with oversight and control of the game and is the authority on the score, the down number, and any rule interpretations in discussions among the other officials. The referee announces all penalties and discusses the infraction with the offending team's captain, monitors for illegal hits against the quarterback, makes requests for first-down measurements, and notifies the head coach whenever a player is ejected. The referee positions themselves to the passing arm side of the quarterback. In most games, the referee is responsible for spotting the football prior to a play from scrimmage.</li>
<li>The <b>umpire</b> is positioned in the defensive backfield, except in the NFL, where the umpire is positioned lateral to the referee on the opposite side of the formation. The umpire watches play along the line of scrimmage to make sure that no more than 11 offensive players are on the field before the snap and that no offensive linemen are <a href="/wiki/Ineligible_receiver_downfield" title="Ineligible receiver downfield">illegally downfield</a> on pass plays. The umpire monitors contact between offensive and defensive linemen and calls most of the <a href="/wiki/Holding_(American_football)" title="Holding (American football)">holding</a> penalties. The umpire records the number of timeouts taken and the winner of the coin toss and the game score, assists the referee in situations involving possession of the ball close to the line of scrimmage, determines whether player equipment is legal, and dries wet balls prior to the snap if a game is played in rain.</li>
<li>The <b>back judge</b> is positioned deep in the defensive backfield, behind the umpire. The back judge ensures that the defensive team has no more than 11 players on the field and determines whether catches are legal, whether field goal or extra point attempts are good, and whether a <a href="/wiki/Pass_interference" title="Pass interference">pass interference</a> violation occurred. The back judge is also responsible for the play clock, the time between each play, when a visible play clock is not used.</li>
<li>The <b>head linesman</b>/<b>down judge</b> is positioned on one end of the line of scrimmage. The head linesman/down judge watches for any line-of-scrimmage and illegal use-of-hands violations and assists the line judge with illegal shift or illegal motion calls. The head linesman/down judge also rules on out-of-bounds calls that happen on their side of the field, oversees the chain crew and marks the forward progress of a runner when a play has been whistled dead.</li></ul><div class="thumb tright"><div class="thumbinner" style="width:172px;"><a href="/wiki/File:First_down_marker.png" class="image"><noscript><img alt="Photograph of a down indicator box on a pole" src="//upload.wikimedia.org/wikipedia/commons/thumb/8/82/First_down_marker.png/170px-First_down_marker.png" decoding="async" width="170" height="249" class="thumbimage" data-file-width="939" data-file-height="1375"></noscript><span class="lazy-image-placeholder" style="width: 170px;height: 249px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/8/82/First_down_marker.png/170px-First_down_marker.png" data-alt="Photograph of a down indicator box on a pole" data-width="170" data-height="249" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:First_down_marker.png" class="internal" title="Enlarge"></a></div>A modern down indicator box is mounted on a pole and is used to mark the current line of scrimmage. The number on the marker is changed using a dial.</div></div></div>
<ul><li>The <b>side judge</b> is positioned twenty yards downfield of the head linesman. The side judge mainly duplicates the functions of the field judge. On field goal and extra point attempts, the side judge is positioned lateral to the umpire.</li>
<li>The <b>line judge</b> is positioned on the end of the line of scrimmage, opposite the head linesman. They supervise player substitutions, the line of scrimmage during punts, and game timing. The line judge notifies the referee when time has expired at the end of a quarter and notifies the head coach of the home team when five minutes remain for halftime. In the NFL, the line judge also alerts the referee when <a href="/wiki/Two-minute_warning" title="Two-minute warning">two minutes remain in the half</a>. If the clock malfunctions or becomes inoperable, the line judge becomes the official timekeeper.</li>
<li>The <b>field judge</b> is positioned twenty yards downfield from the line judge. The field judge monitors and controls the <a href="/wiki/Play_clock" title="Play clock">play clock</a>, counts the number of defensive players on the field and watches for offensive pass interference and illegal use-of-hands violations by offensive players. The field judge also makes decisions regarding catches, recoveries, the ball spot when a player goes out of bounds, and illegal touching of fumbled balls that have crossed the line of scrimmage. On field goal and extra point attempts, the field judge is stationed under the upright opposite the back judge.</li>
<li>The <b>center judge</b> is an eighth official used only in the top level of college football. The center judge stands lateral to the referee, the same way the umpire does in the NFL. The center judge is responsible for spotting the football after each play and has many of the same responsibilities as the referee, except announcing penalties.</li></ul><p>Another set of officials, the <a href="/wiki/Chain_crew" title="Chain crew">chain crew</a>, are responsible for moving the chains. The chains, consisting of two large sticks with a 10-yard-long chain between them, are used to measure for a first down. The chain crew stays on the sidelines during the game, but if requested by the officials they will briefly bring the chains on to the field to measure. A typical chain crew will have at least three people—two members of the chain crew will hold either of the two sticks, while a third will hold the down marker. The down marker, a large stick with a dial on it, is flipped after each play to indicate the current down and is typically moved to the approximate spot of the ball. The chain crew system has been used for over 100 years and is considered to be an accurate measure of distance, rarely subject to criticism from either side.<sup id="cite_ref-The_Orchestration_of_the_Chain_Gang_92-1" class="reference"><a href="#cite_note-The_Orchestration_of_the_Chain_Gang-92">[91]</a></sup></p>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(5)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="Safety_and_brain_health">Safety and brain health</span></h2><section class="mf-section-5 collapsible-block" id="mf-section-5">
<div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Protective_equipment_in_gridiron_football" title="Protective equipment in gridiron football">Protective equipment in gridiron football</a> and <a href="/wiki/Health_issues_in_American_football" title="Health issues in American football">Health issues in American football</a></div>
<div class="thumb tright"><div class="thumbinner" style="width:172px;"><a href="/wiki/File:Vince_Agnew.jpg" class="image"><noscript><img alt="Photograph of a player wearing a helmet, with shoulder pads and thigh pads visible under their uniform" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7c/Vince_Agnew.jpg/170px-Vince_Agnew.jpg" decoding="async" width="170" height="306" class="thumbimage" data-file-width="711" data-file-height="1280"></noscript><span class="lazy-image-placeholder" style="width: 170px;height: 306px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7c/Vince_Agnew.jpg/170px-Vince_Agnew.jpg" data-alt="Photograph of a player wearing a helmet, with shoulder pads and thigh pads visible under their uniform" data-width="170" data-height="306" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:Vince_Agnew.jpg" class="internal" title="Enlarge"></a></div><a href="/wiki/Vince_Agnew" title="Vince Agnew">Vince Agnew</a> wearing a helmet. Shoulder pads and thigh pads are visible under his uniform</div></div></div>
<p>Football is a full-contact sport, and injuries are relatively common. Most injuries occur during training sessions, particularly ones that involve contact between players.<sup id="cite_ref-Sports_Medicine_114-0" class="reference"><a href="#cite_note-Sports_Medicine-114">[113]</a></sup> To try to prevent injuries, players are required to wear a set of equipment. At a minimum players must wear a <a href="/wiki/Football_helmet" title="Football helmet">football helmet</a> and a set of <a href="/wiki/Shoulder_pads" title="Shoulder pads">shoulder pads</a>, but individual leagues may require additional padding such as thigh pads and guards, knee pads, chest protectors, and <a href="/wiki/Mouthguard" title="Mouthguard">mouthguards</a>.<sup id="cite_ref-NFL_Rules_2012,_pp._24-27_115-0" class="reference"><a href="#cite_note-NFL_Rules_2012,_pp._24-27-115">[114]</a></sup><sup id="cite_ref-NCAA_Rules_2011-2012,_p._22_116-0" class="reference"><a href="#cite_note-NCAA_Rules_2011-2012,_p._22-116">[115]</a></sup><sup id="cite_ref-NFHS_Rules_2012,_pp._17-19_117-0" class="reference"><a href="#cite_note-NFHS_Rules_2012,_pp._17-19-117">[116]</a></sup> Most injuries occur in the lower extremities, particularly in the knee, but a significant number also affect the upper extremities. The most common types of injuries are <a href="/wiki/Strain_(injury)" title="Strain (injury)">strains</a>, <a href="/wiki/Sprain" title="Sprain">sprains</a>, <a href="/wiki/Bruise" title="Bruise">bruises</a>, fractures, <a href="/wiki/Joint_dislocation" title="Joint dislocation">dislocations</a>, and <a href="/wiki/Concussion" title="Concussion">concussions</a>.<sup id="cite_ref-Sports_Medicine_114-1" class="reference"><a href="#cite_note-Sports_Medicine-114">[113]</a></sup></p><p>Repeated <a href="/wiki/Concussions_in_American_football" title="Concussions in American football">concussions</a> (and possibly sub-concussive head impacts<sup id="cite_ref-118" class="reference"><a href="#cite_note-118">[117]</a></sup>) can increase a person's risk in later life for CTE (<a href="/wiki/Chronic_traumatic_encephalopathy" title="Chronic traumatic encephalopathy">chronic traumatic encephalopathy</a>) and mental health issues such as <a href="/wiki/Dementia" title="Dementia">dementia</a>, <a href="/wiki/Parkinson%27s_disease" title="Parkinson's disease">Parkinson's disease</a>, and <a href="/wiki/Mood_disorder" title="Mood disorder">depression</a>.<sup id="cite_ref-119" class="reference"><a href="#cite_note-119">[118]</a></sup> Concussions are often caused by helmet-to-helmet or upper-body contact between opposing players, although helmets have prevented more serious injuries such as <a href="/wiki/Skull_fracture" title="Skull fracture">skull fractures</a>.<sup id="cite_ref-Can_Football_Finally_Tackle_Its_Injury_Problem?_120-0" class="reference"><a href="#cite_note-Can_Football_Finally_Tackle_Its_Injury_Problem?-120">[119]</a></sup> Various programs are aiming to reduce concussions by reducing the frequency of helmet-to-helmet hits; <a href="/wiki/USA_Football" title="USA Football">USA Football</a>'s "Heads Up Football" program aims to reduce concussions in youth football by teaching coaches and players about the signs of a concussion, the proper way to wear football equipment and ensure it fits, and proper tackling methods that avoid helmet-to-helmet contact.<sup id="cite_ref-Heads_Up_Football_121-0" class="reference"><a href="#cite_note-Heads_Up_Football-121">[120]</a></sup> However, a study in the <i>Orthopaedic Journal of Sports Medicine</i> found that Heads Up Football was ineffective; the same study noted that more extensive reforms implemented by <a href="/wiki/Pop_Warner_Little_Scholars" title="Pop Warner Little Scholars">Pop Warner Little Scholars</a> and its member teams were effective in significantly reducing concussion rates.<sup id="cite_ref-122" class="reference"><a href="#cite_note-122">[121]</a></sup></p><p>A 2018 study performed by the VA Boston Healthcare System and the <a href="/wiki/Boston_University_School_of_Medicine" title="Boston University School of Medicine">Boston University School of Medicine</a> found that tackle football before age 12 was correlated with earlier onset of symptoms of CTE, but not with symptom severity. More specifically, each year a player played tackle football under age 12 predicted earlier onset of cognitive, behavioral, and mood problems by an average of two and a half years.<sup id="cite_ref-Study_finds_youth_football_tied_to_earlier_symptoms_of_CTE,_ESPN,_April_30,_2018_123-0" class="reference"><a href="#cite_note-Study_finds_youth_football_tied_to_earlier_symptoms_of_CTE,_ESPN,_April_30,_2018-123">[122]</a></sup><sup id="cite_ref-Austin_American-Statesman,_May_25,_2018_124-0" class="reference"><a href="#cite_note-Austin_American-Statesman,_May_25,_2018-124">[123]</a></sup><sup id="cite_ref-Annals_of_Neurology,_30_April_2018_125-0" class="reference"><a href="#cite_note-Annals_of_Neurology,_30_April_2018-125">[124]</a></sup></p>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(6)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="Leagues_and_tournaments">Leagues and tournaments</span></h2><section class="mf-section-6 collapsible-block" id="mf-section-6">
<p>The <a href="/wiki/National_Football_League" title="National Football League">National Football League</a> (NFL) and the <a href="/wiki/National_Collegiate_Athletic_Association" title="National Collegiate Athletic Association">National Collegiate Athletic Association</a> (NCAA) are the most popular football leagues in the United States.<sup id="cite_ref-Oregon_Live_126-0" class="reference"><a href="#cite_note-Oregon_Live-126">[125]</a></sup> The National Football League was founded in 1920<sup id="cite_ref-NFL_founded_in_Canton_127-0" class="reference"><a href="#cite_note-NFL_founded_in_Canton-127">[126]</a></sup> and has since become the largest and most popular sport in the United States.<sup id="cite_ref-China_fast_catching_American_football_fever_128-0" class="reference"><a href="#cite_note-China_fast_catching_American_football_fever-128">[127]</a></sup> The NFL has the highest average attendance of any sporting league in the world, with an average attendance of 66,960 during the <a href="/wiki/2011_NFL_season" title="2011 NFL season">2011 NFL season</a>.<sup id="cite_ref-And_the_silver_goes_to..._129-0" class="reference"><a href="#cite_note-And_the_silver_goes_to...-129">[128]</a></sup> The NFL championship game is called the Super Bowl, and is among the biggest events in club sports worldwide.<sup id="cite_ref-Elite_clubs_on_Uefa_gravy_train_as_Super_Bowl_knocked_off_perch_130-0" class="reference"><a href="#cite_note-Elite_clubs_on_Uefa_gravy_train_as_Super_Bowl_knocked_off_perch-130">[129]</a></sup> It is played between the champions of the <a href="/wiki/National_Football_Conference" title="National Football Conference">National Football Conference</a> (NFC) and the <a href="/wiki/American_Football_Conference" title="American Football Conference">American Football Conference</a> (AFC), and its winner is awarded the <a href="/wiki/Vince_Lombardi_Trophy" title="Vince Lombardi Trophy">Vince Lombardi Trophy</a>.<sup id="cite_ref-Let's_Learn_About:_The_Vince_Lombardi_Trophy_131-0" class="reference"><a href="#cite_note-Let's_Learn_About:_The_Vince_Lombardi_Trophy-131">[130]</a></sup></p>
<div class="thumb tright"><div class="thumbinner" style="width:227px;"><a href="/wiki/File:High_School_Football_Game.jpg" class="image"><noscript><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e3/High_School_Football_Game.jpg/225px-High_School_Football_Game.jpg" decoding="async" width="225" height="169" class="thumbimage" data-file-width="4032" data-file-height="3024"></noscript><span class="lazy-image-placeholder" style="width: 225px;height: 169px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e3/High_School_Football_Game.jpg/225px-High_School_Football_Game.jpg" data-alt="" data-width="225" data-height="169" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:High_School_Football_Game.jpg" class="internal" title="Enlarge"></a></div>A high school football game during the first quarter</div></div></div>
<p><a href="/wiki/College_football" title="College football">College football</a> is the third-most popular sport in the United States, behind professional baseball and professional football.<sup id="cite_ref-Harris_Poll_2012_132-0" class="reference"><a href="#cite_note-Harris_Poll_2012-132">[131]</a></sup> The NCAA, the largest collegiate organization, is divided into three Divisions: <a href="/wiki/NCAA_Division_I" title="NCAA Division I">Division I</a>, <a href="/wiki/NCAA_Division_II" title="NCAA Division II">Division II</a> and <a href="/wiki/NCAA_Division_III" title="NCAA Division III">Division III</a>.<sup id="cite_ref-About_the_NCAA_133-0" class="reference"><a href="#cite_note-About_the_NCAA-133">[132]</a></sup> Division I football is further divided into two subdivisions: the <a href="/wiki/Football_Bowl_Subdivision" class="mw-redirect" title="Football Bowl Subdivision">Football Bowl Subdivision</a> (FBS) and the <a href="/wiki/Football_Championship_Subdivision" class="mw-redirect" title="Football Championship Subdivision">Football Championship Subdivision</a> (FCS).<sup id="cite_ref-Differences_Among_the_Three_Divisions:_Division_I_134-0" class="reference"><a href="#cite_note-Differences_Among_the_Three_Divisions:_Division_I-134">[133]</a></sup> The champions of each level of play are determined through NCAA-sanctioned playoff systems; while the champion of Division I-FBS was historically determined by various polls and ranking systems, the subdivision adopted a four-team playoff system in 2014.<sup id="cite_ref-Postseason_Football_135-0" class="reference"><a href="#cite_note-Postseason_Football-135">[134]</a></sup></p><p><a href="/wiki/High_school_football" title="High school football">High school football</a> is the most popular sport in the United States played by boys; over 1.1 million boys participated in the sport from 2007 to 2008 according to a survey by the <a href="/wiki/National_Federation_of_State_High_School_Associations" title="National Federation of State High School Associations">National Federation of State High School Associations</a> (NFHS). The NFHS is the largest organization for high school football, with member associations in all <a href="/wiki/List_of_states_and_territories_of_the_United_States" title="List of states and territories of the United States">50 states</a> as well as the <a href="/wiki/Washington,_D.C." title="Washington, D.C.">District of Columbia</a>. USA Football is the governing body for youth and amateur football,<sup id="cite_ref-NFHS_and_USA_Football_Create_Football_Coaching_Course_136-0" class="reference"><a href="#cite_note-NFHS_and_USA_Football_Create_Football_Coaching_Course-136">[135]</a></sup> and Pop Warner Little Scholars is the largest organization for youth football.<sup id="cite_ref-Trying_to_Reduce_Head_Injuries,_Youth_Football_Limits_Practices_137-0" class="reference"><a href="#cite_note-Trying_to_Reduce_Head_Injuries,_Youth_Football_Limits_Practices-137">[136]</a></sup></p>
<h3 class="in-block"><span class="mw-headline" id="Other_professional_leagues">Other professional leagues</span></h3>
<p>Several professional football leagues have been formed outside the auspices of the NFL. One such league, the <a href="/wiki/XFL_(2020)" title="XFL (2020)">XFL</a>, is currently operating as of 2020.<sup id="cite_ref-138" class="reference"><a href="#cite_note-138">[137]</a></sup></p>
<h4 class="in-block"><span class="mw-headline" id="Rival_leagues">Rival leagues</span></h4>
<p>The most successful league to directly compete with the NFL was the American Football League (AFL), which existed from 1960 to 1969. The AFL became a significant rival in <a href="/wiki/1964_American_Football_League_season" title="1964 American Football League season">1964</a> before signing a five-year, US$36 million television deal with NBC. AFL teams began signing NFL players to contracts, and the league's popularity grew to challenge that of the NFL. The two leagues merged in the <a href="/wiki/1970_NFL_season" title="1970 NFL season">1970 season</a>, and all the AFL teams joined the NFL. An earlier league, the <a href="/wiki/All-America_Football_Conference" title="All-America Football Conference">All-America Football Conference</a> (AAFC), was in play from 1946 to 1949. After it had dissolved, two AAFC teams, the <a href="/wiki/Cleveland_Browns" title="Cleveland Browns">Cleveland Browns</a> and the <a href="/wiki/San_Francisco_49ers" title="San Francisco 49ers">San Francisco 49ers</a>, became members of the NFL; another member, the <a href="/wiki/Baltimore_Colts_(1947%E2%80%9350)" class="mw-redirect" title="Baltimore Colts (1947–50)">Baltimore Colts</a> joined the league, but folded after just a year in the NFL.<sup id="cite_ref-Off-the-field_competition_yields_game-changing_merger_139-0" class="reference"><a href="#cite_note-Off-the-field_competition_yields_game-changing_merger-139">[138]</a></sup></p><p>Other attempts to start rival leagues since the AFL merged with the NFL in 1970 have been far less successful, as professional football salaries and the <a href="/wiki/NFL_on_television" class="mw-redirect" title="NFL on television">NFL's television contracts</a> began to escalate out of the reach of competitors and the NFL covered more of the larger cities. The <a href="/wiki/World_Football_League" title="World Football League">World Football League</a> (WFL) played for two seasons, in 1974 and 1975, but faced such severe monetary issues it could not pay its players. In its second and final season the WFL attempted to establish a stable credit rating, but the league disbanded before the season could be completed.<sup id="cite_ref-The_Day_The_Money_Ran_Out_140-0" class="reference"><a href="#cite_note-The_Day_The_Money_Ran_Out-140">[139]</a></sup> The <a href="/wiki/United_States_Football_League" title="United States Football League">United States Football League</a> (USFL) operated for three seasons from 1983 to 1985. Originally not intended as a rival league, the entry of owners who sought marquee talent and to challenge the NFL led to an escalation in salaries and ensuing financial losses. A subsequent US$1.5 billion antitrust lawsuit against the NFL was successful in court, but the league was awarded only $1 in damages, which was automatically tripled to $3 under antitrust law.<sup id="cite_ref-Twenty_years_later,_USFL_still_brings_fond_memories_141-0" class="reference"><a href="#cite_note-Twenty_years_later,_USFL_still_brings_fond_memories-141">[140]</a></sup></p>
<h4 class="in-block"><span class="mw-headline" id="Complementary_national_leagues">Complementary national leagues</span></h4>
<p>The original <a href="/wiki/XFL_(2001)" title="XFL (2001)">XFL</a> was created in 2001 by <a href="/wiki/Vince_McMahon" title="Vince McMahon">Vince McMahon</a> and lasted for only one season. Despite television contracts with NBC and <a href="/wiki/UPN" title="UPN">UPN</a>, and high expectations, the XFL suffered from low quality of play and poor reception for its use of <a href="/wiki/Attitude_Era" title="Attitude Era">tawdry professional wrestling gimmicks</a>, which caused initially high ratings and attendance to collapse.<sup id="cite_ref-No_More_Springtimes_for_the_XFL_as_League_Folds_142-0" class="reference"><a href="#cite_note-No_More_Springtimes_for_the_XFL_as_League_Folds-142">[141]</a></sup> (The current XFL, also owned by McMahon, does not include those gimmicks.) The <a href="/wiki/United_Football_League_(2009%E2%80%93)" class="mw-redirect" title="United Football League (2009–)">United Football League</a> (UFL) began in <a href="/wiki/2009_UFL_season" title="2009 UFL season">2009</a> but folded after suspending its <a href="/wiki/2012_UFL_season" title="2012 UFL season">2012 season</a> amid declining interest and lack of major television coverage.<sup id="cite_ref-Just_What_Is_Going_on_with_the_UFL?_143-0" class="reference"><a href="#cite_note-Just_What_Is_Going_on_with_the_UFL?-143">[142]</a></sup> The <a href="/wiki/Alliance_of_American_Football" title="Alliance of American Football">Alliance of American Football</a> lasted <a href="/wiki/2019_AAF_season" title="2019 AAF season">less than one season</a>, unable to keep investors.<sup id="cite_ref-disappointed_144-0" class="reference"><a href="#cite_note-disappointed-144">[143]</a></sup></p>
<h3 class="in-block"><span class="mw-headline" id="International_play">International play</span></h3>
<div class="thumb tright"><div class="thumbinner" style="width:252px;"><a href="/wiki/File:03042012Ccm_gamosuma_juvenilA366.JPG" class="image"><noscript><img alt="Photograph of a Mexican youth division football team" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d8/03042012Ccm_gamosuma_juvenilA366.JPG/250px-03042012Ccm_gamosuma_juvenilA366.JPG" decoding="async" width="250" height="166" class="thumbimage" data-file-width="3008" data-file-height="2000"></noscript><span class="lazy-image-placeholder" style="width: 250px;height: 166px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d8/03042012Ccm_gamosuma_juvenilA366.JPG/250px-03042012Ccm_gamosuma_juvenilA366.JPG" data-alt="Photograph of a Mexican youth division football team" data-width="250" data-height="166" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:03042012Ccm_gamosuma_juvenilA366.JPG" class="internal" title="Enlarge"></a></div>Players with one of the youth divisions of the <a href="/wiki/Borregos_Salvajes" title="Borregos Salvajes">Borregos Salvajes</a> football program of the <a href="/wiki/Monterrey_Institute_of_Technology_and_Higher_Education,_Mexico_City" class="mw-redirect" title="Monterrey Institute of Technology and Higher Education, Mexico City">Monterrey Institute of Technology and Higher Education, Mexico City</a></div></div></div>
<p>American football leagues exist throughout the world, but the game has yet to achieve the international success and popularity of baseball and basketball.<sup id="cite_ref-145" class="reference"><a href="#cite_note-145">[144]</a></sup> It is not an <a href="/wiki/Olympic_sport" class="mw-redirect" title="Olympic sport">Olympic sport</a>, but it was a <a href="/wiki/Demonstration_sport" title="Demonstration sport">demonstration sport</a> at the <a href="/wiki/American_football_at_the_1932_Summer_Olympics" title="American football at the 1932 Summer Olympics">1932 Summer Olympics</a>.<sup id="cite_ref-Football_remains_an_Olympic_long_shot_1-1" class="reference"><a href="#cite_note-Football_remains_an_Olympic_long_shot-1">[1]</a></sup> At the international level, Canada, Mexico, and Japan are considered to be second-tier, while Austria, Germany, and France would rank among a third tier. These countries rank far below the United States, which is dominant at the international level.<sup id="cite_ref-Football_in_Olympics_is_a_dream_that_could_become_a_reality_146-0" class="reference"><a href="#cite_note-Football_in_Olympics_is_a_dream_that_could_become_a_reality-146">[145]</a></sup></p><p><a href="/wiki/NFL_Europe" title="NFL Europe">NFL Europa</a>, the <a href="/wiki/Minor_league" title="Minor league">developmental league</a> of the NFL, operated from 1991 to 1992 and then from 1995 to 2007. At the time of its closure, NFL Europa had five teams based in Germany and one in the Netherlands.<sup id="cite_ref-NFL_Europa_to_cease_operations_147-0" class="reference"><a href="#cite_note-NFL_Europa_to_cease_operations-147">[146]</a></sup> In Germany, the <a href="/wiki/German_Football_League" title="German Football League">German Football League</a> (GFL) has 16 teams and has operated for over 40 seasons, with the league's championship game, the <a href="/wiki/German_Bowl" title="German Bowl">German Bowl</a>, closing out each season. The league operates in a <a href="/wiki/Promotion_and_relegation" title="Promotion and relegation">promotion and relegation</a> structure with <a href="/wiki/German_Football_League_2" title="German Football League 2">German Football League 2</a> (GFL2), which also has 16 teams.<sup id="cite_ref-Vicksburg_148-0" class="reference"><a href="#cite_note-Vicksburg-148">[147]</a></sup> The <a href="/wiki/BIG6_European_Football_League" title="BIG6 European Football League">BIG6 European Football League</a> functions as a continental championship for Europe. The competition is contested between the top six European teams.<sup id="cite_ref-Vicksburg_148-1" class="reference"><a href="#cite_note-Vicksburg-148">[147]</a></sup></p><p>American football federations are present in <a href="/wiki/IFAF_Africa" title="IFAF Africa">Africa</a>, <a href="/wiki/IFAF_Americas" title="IFAF Americas">the Americas</a>, <a href="/wiki/IFAF_Asia" title="IFAF Asia">Asia</a>, <a href="/wiki/IFAF_Europe" title="IFAF Europe">Europe</a>  and <a href="/wiki/IFAF_Oceania" title="IFAF Oceania">Oceania</a>; a total of 64 national football federations exist as of July 2012.<sup id="cite_ref-Football_in_Olympics_is_a_dream_that_could_become_a_reality_146-1" class="reference"><a href="#cite_note-Football_in_Olympics_is_a_dream_that_could_become_a_reality-146">[145]</a></sup> The <a href="/wiki/International_Federation_of_American_Football" title="International Federation of American Football">International Federation of American Football</a> (IFAF), an international governing body composed of continental federations, runs tournaments such as the <a href="/wiki/IFAF_World_Championship" title="IFAF World Championship">IFAF World Championship</a>, the <a href="/wiki/IFAF_Women%27s_World_Championship" title="IFAF Women's World Championship">IFAF Women's World Championship</a>, the <a href="/wiki/IFAF_U-19_World_Cup" title="IFAF U-19 World Cup">IFAF U-19 World Championship</a> and the <a href="/wiki/IFAF_Flag_Football_World_Championship" title="IFAF Flag Football World Championship">Flag Football World Championship</a>. The IFAF also organizes the annual International Bowl game.<sup id="cite_ref-Championship_Competitions_149-0" class="reference"><a href="#cite_note-Championship_Competitions-149">[148]</a></sup> The IFAF has received provisional recognition from the <a href="/wiki/International_Olympic_Committee" title="International Olympic Committee">International Olympic Committee</a> (IOC).<sup id="cite_ref-Football_takes_step_toward_Olympics,_could_be_medal_sport_in_2024_150-0" class="reference"><a href="#cite_note-Football_takes_step_toward_Olympics,_could_be_medal_sport_in_2024-150">[149]</a></sup> Several major obstacles hinder the IFAF goal of achieving status as an Olympic sport. These include the predominant participation of men in international play and the short three-week Olympic schedule. Large team sizes are an additional difficulty, due to the Olympics' set limit of 10,500 athletes and coaches. American football also has an issue with a lack of global visibility. <a href="/wiki/Nigel_Melville" title="Nigel Melville">Nigel Melville</a>, the CEO of <a href="/wiki/USA_Rugby" title="USA Rugby">USA Rugby</a>, noted that "American football is recognized globally as a sport, but it's not played globally." To solve these concerns, major effort has been put into promoting <a href="/wiki/Flag_football" title="Flag football">flag football</a>, a modified version of American football, at the international level.<sup id="cite_ref-Football_in_Olympics_is_a_dream_that_could_become_a_reality_146-2" class="reference"><a href="#cite_note-Football_in_Olympics_is_a_dream_that_could_become_a_reality-146">[145]</a></sup></p>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(7)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="Popularity_and_cultural_impact">Popularity and cultural impact</span></h2><section class="mf-section-7 collapsible-block" id="mf-section-7">
<h3 class="in-block"><span class="mw-headline" id="United_States">United States</span></h3>
<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/American_football_in_the_United_States" title="American football in the United States">American football in the United States</a></div>
<p>"Baseball is still called the national pastime, but football is by far the more popular sport in American society", according to ESPN.com's Sean McAdam.<sup id="cite_ref-Football_leaving_baseball_in_the_dust_151-0" class="reference"><a href="#cite_note-Football_leaving_baseball_in_the_dust-151">[150]</a></sup> In a 2014 poll conducted by <a href="/wiki/Harris_Insights_%26_Analytics" title="Harris Insights & Analytics">Harris Interactive</a>, professional football ranked as the most popular sport, and college football ranked third behind only professional football and baseball; 46% of participants ranked some form of the game as their favorite sport. Professional football has ranked as the most popular sport in the poll since 1985, when it surpassed baseball for the first time.<sup id="cite_ref-NFL_most_popular_for_30th_year_in_row_152-0" class="reference"><a href="#cite_note-NFL_most_popular_for_30th_year_in_row-152">[151]</a></sup> Professional football is most popular among those who live in the eastern United States and rural areas, while college football is most popular in the southern United States and among people with graduate and post-graduate degrees.<sup id="cite_ref-As_American_as_Mom,_Apple_Pie_and_Football?_153-0" class="reference"><a href="#cite_note-As_American_as_Mom,_Apple_Pie_and_Football?-153">[152]</a></sup> Football is also the most-played sport by high school and college athletes in the United States. In a 2012 study, the NCAA estimated there were around 1.1 million high school football players and nearly 70,000 college football players in the United States; in comparison, the second-most played sport, basketball, had around 1 million participants in high school and 34,000 in college.<sup id="cite_ref-Estimated_Probability_of_Competing_in_Athletics_Beyond_the_High_School_Interscholastic_Level_154-0" class="reference"><a href="#cite_note-Estimated_Probability_of_Competing_in_Athletics_Beyond_the_High_School_Interscholastic_Level-154">[153]</a></sup> The Super Bowl is the most popular single-day sporting event in the United States,<sup id="cite_ref-The_Second_25_Years_31-1" class="reference"><a href="#cite_note-The_Second_25_Years-31">[30]</a></sup> and is among the biggest club sporting events in the world in terms of TV viewership.<sup id="cite_ref-Elite_clubs_on_Uefa_gravy_train_as_Super_Bowl_knocked_off_perch_130-1" class="reference"><a href="#cite_note-Elite_clubs_on_Uefa_gravy_train_as_Super_Bowl_knocked_off_perch-130">[129]</a></sup> The NFL makes approximately $10 billion annually.<sup id="cite_ref-NFL_takes_aim_at_$25_billion,_but_at_what_price?_155-0" class="reference"><a href="#cite_note-NFL_takes_aim_at_%2425_billion,_but_at_what_price?-155">[154]</a></sup> Super Bowl games account for seven of the top eight most-watched broadcasts in American history; <a href="/wiki/Super_Bowl_XLIX" title="Super Bowl XLIX">Super Bowl XLIX</a>, played on February 1, 2015, was watched by a record 114.4 million Americans.<sup id="cite_ref-Super_Bowl_XLIX_156-0" class="reference"><a href="#cite_note-Super_Bowl_XLIX-156">[155]</a></sup></p><p>American football also plays a significant role in American culture. The day on which the Super Bowl is held is considered <a href="/wiki/Super_Bowl_Sunday" title="Super Bowl Sunday">a <i>de facto</i> national holiday</a>,<sup id="cite_ref-NFL_has_made_Super_Bowl_Sunday_into_a_holiday,_is_a_three-day_weekend_the_next_step?_157-0" class="reference"><a href="#cite_note-NFL_has_made_Super_Bowl_Sunday_into_a_holiday,_is_a_three-day_weekend_the_next_step?-157">[156]</a></sup> and in parts of the country like <a href="/wiki/Texas" title="Texas">Texas</a>, the sport has been compared to a religion.<sup id="cite_ref-In_Texas,_High_School_Football_Is_King_158-0" class="reference"><a href="#cite_note-In_Texas,_High_School_Football_Is_King-158">[157]</a></sup><sup id="cite_ref-A_$60_Million_Palace_for_Texas_High_School_Football_159-0" class="reference"><a href="#cite_note-A_%2460_Million_Palace_for_Texas_High_School_Football-159">[158]</a></sup> Football is also linked to other holidays; New Year's Day is traditionally the date for several college football bowl games, including the <a href="/wiki/Rose_Bowl_Game" title="Rose Bowl Game">Rose Bowl</a>. However, if New Year's Day is on a Sunday, the bowl games are moved to another date so as not to conflict with the typical NFL Sunday schedule.<sup id="cite_ref-No_New_Year's_Day_Bowl_Games?_Bah,_Humbug_160-0" class="reference"><a href="#cite_note-No_New_Year's_Day_Bowl_Games?_Bah,_Humbug-160">[159]</a></sup> <a href="/wiki/Thanksgiving_(United_States)" title="Thanksgiving (United States)">Thanksgiving</a> <a href="/wiki/American_football_on_Thanksgiving" title="American football on Thanksgiving">football</a> is an American tradition,<sup id="cite_ref-From_Macy's_to_NFL,_Thanksgiving_traditions_explained_161-0" class="reference"><a href="#cite_note-From_Macy's_to_NFL,_Thanksgiving_traditions_explained-161">[160]</a></sup> hosting many high school, college, and professional games.<sup id="cite_ref-Thanksgiving_and_Football:_A_Unique_American_Tradition_162-0" class="reference"><a href="#cite_note-Thanksgiving_and_Football:_A_Unique_American_Tradition-162">[161]</a></sup> Steve Deace of <i><a href="/wiki/USA_Today" title="USA Today">USA Today</a></i> wrote that Americans are passionate about football "because it embodies everything we love about <a href="/wiki/American_exceptionalism" title="American exceptionalism">American exceptionalism</a>. Merit is rewarded, not punished. Masculinity is celebrated, not feminized. People of various beliefs and backgrounds – a melting pot, if you will – must unify for a common goal for the team to be successful".<sup id="cite_ref-Football_celebrates_masculinity_163-0" class="reference"><a href="#cite_note-Football_celebrates_masculinity-163">[162]</a></sup> Implicit rules such as playing through pain and sacrificing for the better of the team are promoted in football culture.<sup id="cite_ref-164" class="reference"><a href="#cite_note-164">[163]</a></sup></p><p>The safety of the sport has also sparked national controversy in <a href="/wiki/American_popular_culture" class="mw-redirect" title="American popular culture">American popular culture</a>. It is often received as "overly aggressive", and <a href="/wiki/Defamiliarization" title="Defamiliarization">defamiliarized</a> in popular culture.<sup id="cite_ref-165" class="reference"><a href="#cite_note-165">[164]</a></sup> The 2015 film <i><a href="/wiki/Concussion_(2015_film)" title="Concussion (2015 film)">Concussion</a></i> aimed to shed light on the sport's safety, specifically in the NFL by having <a href="/wiki/Will_Smith" title="Will Smith">Will Smith</a> portray <a href="/wiki/Bennet_Omalu" title="Bennet Omalu">Dr. Bennet Omalu</a>, a <a href="/wiki/Neuropathologist" class="mw-redirect" title="Neuropathologist">neuropathologist</a> who was the first to discover and publish findings of chronic traumatic encephalopathy or CTE.
</p>
<h3 class="in-block"><span class="mw-headline" id="Other_countries">Other countries</span></h3>
<p>In Canada, the game has a significant following. According to a 2013 poll, 21% of respondents said they followed the NFL "very closely" or "fairly closely", making it the third-most followed league behind the <a href="/wiki/National_Hockey_League" title="National Hockey League">National Hockey League</a> (NHL) and <a href="/wiki/Canadian_Football_League" title="Canadian Football League">Canadian Football League</a> (CFL).<sup id="cite_ref-Super_Bowl_2014:_Comparing_the_NFL's_popularity_in_Canada_and_the_U.S._166-0" class="reference"><a href="#cite_note-Super_Bowl_2014:_Comparing_the_NFL's_popularity_in_Canada_and_the_U.S.-166">[165]</a></sup> American football also has a long history in Mexico, which was introduced to the sport in 1896. It was the second-most popular sport in Mexico in the 1950s, with the game being particularly popular in colleges.<sup id="cite_ref-Mexico's_long_love_affair_with_football,_American-style_167-0" class="reference"><a href="#cite_note-Mexico's_long_love_affair_with_football,_American-style-167">[166]</a></sup> The <i><a href="/wiki/Los_Angeles_Times" title="Los Angeles Times">Los Angeles Times</a></i> notes the NFL claims over 16 million fans in Mexico, which places the country third behind the US and Canada.<sup id="cite_ref-NFL's_popularity_in_Mexico_continues_to_grow_168-0" class="reference"><a href="#cite_note-NFL's_popularity_in_Mexico_continues_to_grow-168">[167]</a></sup> American football is played in Mexico both professionally and as part of the college sports system.<sup id="cite_ref-American_football_touches_down_in_Germany_169-0" class="reference"><a href="#cite_note-American_football_touches_down_in_Germany-169">[168]</a></sup> A professional league, the <a href="/wiki/Liga_de_F%C3%BAtbol_Americano_Profesional" title="Liga de Fútbol Americano Profesional">Liga de Fútbol Americano Profesional</a> (LFA), was founded in 2016.<sup id="cite_ref-170" class="reference"><a href="#cite_note-170">[169]</a></sup></p>
<div class="thumb tright"><div class="thumbinner" style="width:252px;"><a href="/wiki/File:NFL_International_Series_2010.jpg" class="image"><noscript><img alt="Photograph of London's Wembley Stadium during the opening ceremony of the 2010 NFL International series showing the field and the stands filled with fans" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3d/NFL_International_Series_2010.jpg/250px-NFL_International_Series_2010.jpg" decoding="async" width="250" height="166" class="thumbimage" data-file-width="1024" data-file-height="680"></noscript><span class="lazy-image-placeholder" style="width: 250px;height: 166px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3d/NFL_International_Series_2010.jpg/250px-NFL_International_Series_2010.jpg" data-alt="Photograph of London's Wembley Stadium during the opening ceremony of the 2010 NFL International series showing the field and the stands filled with fans" data-width="250" data-height="166" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:NFL_International_Series_2010.jpg" class="internal" title="Enlarge"></a></div>Opening ceremony of the 2010 <a href="/wiki/NFL_International_Series" title="NFL International Series">NFL International Series</a> at London's <a href="/wiki/Wembley_Stadium" title="Wembley Stadium">Wembley Stadium</a></div></div></div>
<p>Japan was introduced to the sport in 1934 by <a href="/wiki/Paul_Rusch" title="Paul Rusch">Paul Rusch</a>, a teacher and Christian missionary who helped to establish football teams at three universities in Tokyo. Play was halted during World War II, but the sport began growing in popularity again after the war. As of 2010<sup class="plainlinks noexcerpt noprint asof-tag update" style="display:none;"><a class="external text" href="https://en.wikipedia.org/w/index.php?title=American_football&action=edit">[update]</a></sup>, there are more than 400 high school football teams in Japan, with over 15,000 participants, and over 100 teams play in the Kantoh Collegiate Football Association (KCFA).<sup id="cite_ref-Friday_night_lights:_American_football_in_Japan_a_high_school_hit_171-0" class="reference"><a href="#cite_note-Friday_night_lights:_American_football_in_Japan_a_high_school_hit-171">[170]</a></sup> The college champion plays the champion of the <a href="/wiki/X-League" title="X-League">X-League</a> (a semi-professional league where teams are financed by corporations) in the <a href="/wiki/Rice_Bowl" title="Rice Bowl">Rice Bowl</a> to determine Japan's national champion.<sup id="cite_ref-Obic_captures_third_straight_Rice_Bowl_172-0" class="reference"><a href="#cite_note-Obic_captures_third_straight_Rice_Bowl-172">[171]</a></sup></p><p>Europe is a major target for the expansion of the game by football organizers. In the United Kingdom in the 1980s, the sport was popular, with the 1986 Super Bowl being watched by over four million people (about 1 out of every 14 Britons). Its popularity faded during the 1990s, coinciding with the establishment of the <a href="/wiki/Premier_League" title="Premier League">Premier League</a>—top level of the <a href="/wiki/English_football_league_system" title="English football league system">English football league system</a>. According to <a href="/wiki/BBC_America" title="BBC America">BBC America</a>, there is a "social stigma" surrounding American football in the UK, with many Brits feeling the sport has no right to call itself "football" due to the lack of emphasis on kicking.<sup id="cite_ref-Touchdown_in_the_U.K.:_Britain's_Long-Distance_Affair_with_the_NFL_173-0" class="reference"><a href="#cite_note-Touchdown_in_the_U.K.:_Britain's_Long-Distance_Affair_with_the_NFL-173">[172]</a></sup> Nonetheless, the sport has retained a following in the United Kingdom; the NFL operates a media network in the country, and since 2007 has hosted the <a href="/wiki/NFL_International_Series" title="NFL International Series">NFL International Series</a> in London. Super Bowl viewership has also rebounded, with over 4.4 million Britons watching <a href="/wiki/Super_Bowl_XLVI" title="Super Bowl XLVI">Super Bowl XLVI</a>.<sup id="cite_ref-Super_Bowl_caps_UK's_growing_gridiron_fever_174-0" class="reference"><a href="#cite_note-Super_Bowl_caps_UK's_growing_gridiron_fever-174">[173]</a></sup> The sport is played in European countries like Switzerland, which has American football clubs in every major city,<sup id="cite_ref-The_Game_Is_American,_but_the_View,_Alpine_175-0" class="reference"><a href="#cite_note-The_Game_Is_American,_but_the_View,_Alpine-175">[174]</a></sup> and Germany, where the sport has around 45,000 registered amateur players.<sup id="cite_ref-American_football_touches_down_in_Germany_169-1" class="reference"><a href="#cite_note-American_football_touches_down_in_Germany-169">[168]</a></sup></p><p>In <a href="/wiki/American_football_in_Brazil" title="American football in Brazil">Brazil</a>, football is a growing sport. It was generally unknown there until the 1980s when a small group of players began playing on <a href="/wiki/Copacabana,_Rio_de_Janeiro#Copacabana_Beach" title="Copacabana, Rio de Janeiro">Copacabana Beach</a> in <a href="/wiki/Rio_de_Janeiro" title="Rio de Janeiro">Rio de Janeiro</a>. The sport grew gradually with 700 amateur players registering within 20 years. Games were played on the beach with modified rules and without the traditional football equipment due to its lack of availability in Brazil. Eventually, a tournament, the Carioca championship, was founded, with the championship <a href="/wiki/Carioca_Bowl" title="Carioca Bowl">Carioca Bowl</a> played to determine a league champion. The country saw its first full-pad game of football in October 2008.<sup id="cite_ref-176" class="reference"><a href="#cite_note-176">[175]</a></sup> According to <i><a href="/wiki/The_Rio_Times" title="The Rio Times">The Rio Times</a></i>, the sport is one of the fastest-growing sports in Brazil and is almost as commonly played as soccer on the beaches of Copacabana and <a href="/wiki/Botafogo" title="Botafogo">Botafogo</a>.<sup id="cite_ref-Rio_177-0" class="reference"><a href="#cite_note-Rio-177">[176]</a></sup></p><p>Football in Brazil is governed by the <a href="/wiki/Confedera%C3%A7%C3%A3o_Brasileira_de_Futebol_Americano" class="mw-redirect" title="Confederação Brasileira de Futebol Americano">Confederação Brasileira de Futebol Americano</a> (CBFA), which had over 5,000 registered players as of November 2013. The sport's increase in popularity has been attributed to games aired on <a href="/wiki/ESPN" title="ESPN">ESPN</a>, which began airing in Brazil in 1992 with Portuguese commentary.<sup id="cite_ref-178" class="reference"><a href="#cite_note-178">[177]</a></sup> The popularity and "easy accessibility" of non-contact versions of the sport in Brazil has led to a rise in participation by female players.<sup id="cite_ref-Rio_177-1" class="reference"><a href="#cite_note-Rio-177">[176]</a></sup> According to ESPN, the American football audience in Brazil increased 800% between 2013 and 2016. The network, along with <a href="/wiki/Esporte_Interativo" title="Esporte Interativo">Esporte Interativo</a>, airs games there on cable television. Football is often associated in Brazil as being the sport of supermodel <a href="/wiki/Gisele_B%C3%BCndchen" title="Gisele Bündchen">Gisele Bündchen</a>'s husband <a href="/wiki/Tom_Brady" title="Tom Brady">Tom Brady</a>. The NFL has expressed interest in having games in the country, and the Super Bowl has become a widely watched event in Brazil at bars and <a href="/wiki/Movie_theater" title="Movie theater">movie theaters</a>.<sup id="cite_ref-Crescimento_do_interesse_por_futebol_americano_no_Brasil_atrai_NFL_179-0" class="reference"><a href="#cite_note-Crescimento_do_interesse_por_futebol_americano_no_Brasil_atrai_NFL-179">[178]</a></sup></p>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(8)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="Variations_and_related_sports">Variations and related sports</span></h2><section class="mf-section-8 collapsible-block" id="mf-section-8">
<div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Canadian_football" title="Canadian football">Canadian football</a>, <a href="/wiki/Arena_football" title="Arena football">Arena football</a>, and <a href="/wiki/Flag_football" title="Flag football">Flag football</a></div>
<div class="thumb tleft"><div class="thumbinner" style="width:222px;"><a href="/wiki/File:US_Navy_111202-N-FC065-001_Cmdr._Bill_Mallory_tries_for_more_yards_after_a_reception_during_a_flag_football_game_celebrating_the_annual_Army-Navy_f.jpg" class="image"><noscript><img alt="Photograph of men playing flag football" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/31/US_Navy_111202-N-FC065-001_Cmdr._Bill_Mallory_tries_for_more_yards_after_a_reception_during_a_flag_football_game_celebrating_the_annual_Army-Navy_f.jpg/220px-US_Navy_111202-N-FC065-001_Cmdr._Bill_Mallory_tries_for_more_yards_after_a_reception_during_a_flag_football_game_celebrating_the_annual_Army-Navy_f.jpg" decoding="async" width="220" height="157" class="thumbimage" data-file-width="2100" data-file-height="1500"></noscript><span class="lazy-image-placeholder" style="width: 220px;height: 157px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/3/31/US_Navy_111202-N-FC065-001_Cmdr._Bill_Mallory_tries_for_more_yards_after_a_reception_during_a_flag_football_game_celebrating_the_annual_Army-Navy_f.jpg/220px-US_Navy_111202-N-FC065-001_Cmdr._Bill_Mallory_tries_for_more_yards_after_a_reception_during_a_flag_football_game_celebrating_the_annual_Army-Navy_f.jpg" data-alt="Photograph of men playing flag football" data-width="220" data-height="157" data-class="thumbimage"> </span></a>  <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:US_Navy_111202-N-FC065-001_Cmdr._Bill_Mallory_tries_for_more_yards_after_a_reception_during_a_flag_football_game_celebrating_the_annual_Army-Navy_f.jpg" class="internal" title="Enlarge"></a></div>Men playing a game of flag football</div></div></div>
<p><a href="/wiki/Canadian_football" title="Canadian football">Canadian football</a>, the predominant form of football in Canada, is closely related to American football—both sports developed from rugby and are considered to be the chief variants of gridiron football.<sup id="cite_ref-Encyclopædia_Britannica_180-0" class="reference"><a href="#cite_note-Encyclop%C3%A6dia_Britannica-180">[179]</a></sup> Although both games share a <a href="/wiki/Comparison_of_American_and_Canadian_football" title="Comparison of American and Canadian football">similar set of rules</a>, there are several key rule differences: for example, in Canadian football the field measures 150 by 65 yards (137 by 59 m), including two 20-yard end zones (for a distance between goal lines of 110 yards),<sup id="cite_ref-Argos,_Rogers_Centre_agree_on_lease_deal_through_2017_181-0" class="reference"><a href="#cite_note-Argos,_Rogers_Centre_agree_on_lease_deal_through_2017-181">[180]</a></sup> teams have three downs instead of four, there are twelve players on each side instead of eleven,<sup id="cite_ref-Behind_IDFFL,_Canadian_players_chase_football_dreams_182-0" class="reference"><a href="#cite_note-Behind_IDFFL,_Canadian_players_chase_football_dreams-182">[181]</a></sup> fair catches are not allowed, and a <a href="/wiki/Single_(football)" title="Single (football)">rouge</a>, worth a single point is scored if the offensive team kicks the ball out of the defense's end zone.<sup id="cite_ref-Head_to_Head:_CFL_vs._NFL_183-0" class="reference"><a href="#cite_note-Head_to_Head:_CFL_vs._NFL-183">[182]</a></sup> The Canadian Football League (CFL) is the major Canadian league and is the second-most popular sporting league in Canada, behind the National Hockey League.<sup id="cite_ref-Head_to_Head:_CFL_vs._NFL_183-1" class="reference"><a href="#cite_note-Head_to_Head:_CFL_vs._NFL-183">[182]</a></sup> The NFL and CFL had a formal working relationship from 1997 to 2006.<sup id="cite_ref-184" class="reference"><a href="#cite_note-184">[183]</a></sup> The CFL has a strategic partnership with two American football leagues, the German Football League (GFL) and the Liga du Futbol Americano Professional (LFA).<sup id="cite_ref-185" class="reference"><a href="#cite_note-185">[184]</a></sup> The Canadian rules were developed separately from the American game.
</p><p><a href="/wiki/Indoor_American_football" title="Indoor American football">Indoor football</a> leagues constitute what <i><a href="/wiki/The_New_York_Times" title="The New York Times">The New York Times</a></i> writer Mike Tanier described as the "most minor of minor leagues." Leagues are unstable, with franchises regularly moving from one league to another or merging with other teams, and teams or entire leagues dissolving completely; games are only attended by a small number of fans, and most players are <a href="/wiki/Semi-professional" class="mw-redirect" title="Semi-professional">semi-professional</a> athletes. The <a href="/wiki/Indoor_Football_League" title="Indoor Football League">Indoor Football League</a> is an example of a prominent indoor league.<sup id="cite_ref-Staying_in_the_Game_on_Football's_Fringe_186-0" class="reference"><a href="#cite_note-Staying_in_the_Game_on_Football's_Fringe-186">[185]</a></sup> The <a href="/wiki/Arena_Football_League" title="Arena Football League">Arena Football League</a>, which was founded in 1987 and ceased operations in 2019, was one of the longest-lived indoor football leagues.<sup id="cite_ref-GleesonChap7_187-0" class="reference"><a href="#cite_note-GleesonChap7-187">[186]</a></sup> In 2004, the league was called "America's fifth major sport" by <i><a href="/wiki/ESPN_The_Magazine" title="ESPN The Magazine">ESPN The Magazine</a></i>.<sup id="cite_ref-Arena_football:_Is_it_America's_fifth_major_sport?_188-0" class="reference"><a href="#cite_note-Arena_football:_Is_it_America's_fifth_major_sport?-188">[187]</a></sup></p><p>There are several non-contact variants of football like flag football.<sup id="cite_ref-NFL_FLAG_football_is_about_fun_and_fundamentals_189-0" class="reference"><a href="#cite_note-NFL_FLAG_football_is_about_fun_and_fundamentals-189">[188]</a></sup> In flag football the ballcarrier is not tackled; instead, defenders aim to pull a flag tied around their waist.<sup id="cite_ref-Proper_flag_pull_takes_fast_feet_and_discipline_190-0" class="reference"><a href="#cite_note-Proper_flag_pull_takes_fast_feet_and_discipline-190">[189]</a></sup> Another variant, <a href="/wiki/Touch_football_(American)" title="Touch football (American)">touch football</a>, simply requires the ballcarrier to be touched to be considered downed. Depending on the rules used, a game of touch football may require the player be touched with either one or two hands to be considered down.<sup id="cite_ref-The_32_Rules_of_Thanksgiving_Touch_Football_191-0" class="reference"><a href="#cite_note-The_32_Rules_of_Thanksgiving_Touch_Football-191">[190]</a></sup></p>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(9)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="See_also">See also</span></h2><section class="mf-section-9 collapsible-block" id="mf-section-9">
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<ul><li><span><noscript><img alt="icon" src="//upload.wikimedia.org/wikipedia/commons/thumb/1/16/American_football.svg/28px-American_football.svg.png" decoding="async" width="28" height="28" class="noviewer" data-file-width="512" data-file-height="512"></noscript><span class="lazy-image-placeholder" style="width: 28px;height: 28px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/1/16/American_football.svg/28px-American_football.svg.png" data-alt="icon" data-width="28" data-height="28" data-srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/16/American_football.svg/42px-American_football.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/16/American_football.svg/56px-American_football.svg.png 2x" data-class="noviewer"> </span></span><span><a href="/wiki/Portal:American_football" title="Portal:American football">American football portal</a></span></li></ul></div>
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<ul><li><a href="/wiki/American_football_strategy" title="American football strategy">American football strategy</a></li>
<li><a href="/wiki/College_football" title="College football">College football</a></li>
<li><a href="/wiki/Comparison_of_American_football_and_rugby_union" title="Comparison of American football and rugby union">Comparison of American football and rugby union</a></li>
<li><a href="/wiki/Comparison_of_American_football_and_rugby_league" title="Comparison of American football and rugby league">Comparison of American football and rugby league</a></li>
<li><a href="/wiki/Concussions_in_American_football" title="Concussions in American football">Concussions in American football</a></li>
<li><a href="/wiki/Fantasy_football_(American)" class="mw-redirect" title="Fantasy football (American)">Fantasy football (American)</a></li>
<li><a href="/wiki/Glossary_of_American_football" title="Glossary of American football">Glossary of American football</a></li>
<li><a href="/wiki/List_of_American_football_players" class="mw-redirect" title="List of American football players">List of American football players</a></li>
<li><a href="/wiki/List_of_American_football_stadiums_by_capacity" title="List of American football stadiums by capacity">List of American football stadiums by capacity</a></li>
<li><a href="/wiki/List_of_leagues_of_American_and_Canadian_football" class="mw-redirect" title="List of leagues of American and Canadian football">List of leagues of American and Canadian football</a></li>
<li><a href="/wiki/Pro_Football_Hall_of_Fame" title="Pro Football Hall of Fame">Pro Football Hall of Fame</a></li>
<li><a href="/wiki/Steroid_use_in_American_football" class="mw-redirect" title="Steroid use in American football">Steroid use in American football</a></li></ul>
 
<table class="multicol" role="presentation" style="border-collapse: collapse; padding: 0; border: 0; background:transparent; width:100%;"><tbody><tr><td></td></tr></tbody></table></div>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(10)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="Notes">Notes</span></h2><section class="mf-section-10 collapsible-block" id="mf-section-10">
<div class="reflist" style="list-style-type: decimal;">
<div class="mw-references-wrap"><ol class="references"><li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text">The terms "<a href="/wiki/Gridiron_football" title="Gridiron football">gridiron football</a>" and "gridiron" are sometimes used as synonyms for American football,<sup id="cite_ref-2" class="reference"><a href="#cite_note-2">[2]</a></sup> and are also sometimes used in a broader sense that includes <a href="/wiki/Canadian_football" title="Canadian football">Canadian football</a> as well.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3">[3]</a></sup></span>
</li>
</ol></div></div>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(11)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="Footnotes">Footnotes</span></h2><section class="mf-section-11 collapsible-block" id="mf-section-11">
<div class="reflist" style="list-style-type: decimal;">
<div class="mw-references-wrap mw-references-columns"><ol class="references"><li id="cite_note-Football_remains_an_Olympic_long_shot-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-Football_remains_an_Olympic_long_shot_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Football_remains_an_Olympic_long_shot_1-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite class="citation web">Florio, Mike (July 27, 2012). <a rel="nofollow" class="external text" href="http://profootballtalk.nbcsports.com/2012/07/27/football-remains-an-olympic-longshot/">"Football remains an Olympic long shot"</a>. <i>Pro Football Talk</i>. <a href="/wiki/NBC_Sports" title="NBC Sports">NBC Sports</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20121230101702/http://profootballtalk.nbcsports.com/2012/07/27/football-remains-an-olympic-longshot/">Archived</a> from the original on December 30, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">January 14,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Pro+Football+Talk&rft.atitle=Football+remains+an+Olympic+long+shot&rft.date=2012-07-27&rft.aulast=Florio&rft.aufirst=Mike&rft_id=http%3A%2F%2Fprofootballtalk.nbcsports.com%2F2012%2F07%2F27%2Ffootball-remains-an-olympic-longshot%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><style data-mw-deduplicate="TemplateStyles:r935243608">.mw-parser-output cite.citation{font-style:inherit}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .id-lock-free a,.mw-parser-output .citation .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .id-lock-limited a,.mw-parser-output .id-lock-registration a,.mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .id-lock-subscription a,.mw-parser-output .citation .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/12px-Wikisource-logo.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-maint{display:none;color:#33aa33;margin-left:0.3em}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}</style></span>
</li>
<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.macmillandictionary.com/us/dictionary/american/gridiron">"Gridiron"</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20171107025727/https://www.macmillandictionary.com/us/dictionary/american/gridiron">Archived</a> November 7, 2017, at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>, <i><a href="/wiki/Macmillan_English_Dictionary_for_Advanced_Learners" title="Macmillan English Dictionary for Advanced Learners">MacMillan Dictionary</a></i></span>
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<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.britannica.com/EBchecked/topic/212839/gridiron-football">"gridiron football (sport)"</a>. <i>Britannica Online Encyclopedia</i>. britannica.com. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20100614053218/http://www.britannica.com/EBchecked/topic/212839/gridiron-football">Archived</a> from the original on June 14, 2010<span class="reference-accessdate">. Retrieved <span class="nowrap">July 13,</span> 2010</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Britannica+Online+Encyclopedia&rft.atitle=gridiron+football+%28sport%29&rft_id=http%3A%2F%2Fwww.britannica.com%2FEBchecked%2Ftopic%2F212839%2Fgridiron-football&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Football_Or_Soccer?_What’s_In_A_Name?-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-Football_Or_Soccer?_What%E2%80%99s_In_A_Name?_5-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Peralta, Eyder (June 10, 2010). <a rel="nofollow" class="external text" href="http://www.npr.org/blogs/showmeyourcleats/2010/06/10/127738094/football-or-soccer-what-s-in-a-name">"Football Or Soccer? What's In A Name?"</a>. <a href="/wiki/NPR" title="NPR">NPR</a><span class="reference-accessdate">. Retrieved <span class="nowrap">April 19,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Football+Or+Soccer%3F+What%27s+In+A+Name%3F&rft.pub=NPR&rft.date=2010-06-10&rft.aulast=Peralta&rft.aufirst=Eyder&rft_id=http%3A%2F%2Fwww.npr.org%2Fblogs%2Fshowmeyourcleats%2F2010%2F06%2F10%2F127738094%2Ffootball-or-soccer-what-s-in-a-name&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text">Nelson 1993, pp. 15, 22.</span>
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<li id="cite_note-'In_the_six'_and_football's_other_strange_Americanisms-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-'In_the_six'_and_football's_other_strange_Americanisms_7-0">^</a></b></span> <span class="reference-text"><cite class="citation news">Geoghegan, Tim (May 27, 2013). <a rel="nofollow" class="external text" href="https://www.bbc.co.uk/news/magazine-22633980">"<span class="cs1-kern-left">'</span>In the six' and football's other strange Americanisms"</a>. <a href="/wiki/BBC_News" title="BBC News">BBC News</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130609180830/http://www.bbc.co.uk/news/magazine-22633980">Archived</a> from the original on June 9, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">June 28,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=%27In+the+six%27+and+football%27s+other+strange+Americanisms&rft.date=2013-05-27&rft.aulast=Geoghegan&rft.aufirst=Tim&rft_id=https%3A%2F%2Fwww.bbc.co.uk%2Fnews%2Fmagazine-22633980&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Living_off_the_grid:_American_football_in_coastal_Australia-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-Living_off_the_grid:_American_football_in_coastal_Australia_8-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Huntsdale, Justin (June 13, 2012). <a rel="nofollow" class="external text" href="http://www.abc.net.au/local/stories/2012/06/13/3524011.htm">"Living off the grid: American football in coastal Australia"</a>. <a href="/wiki/Australian_Broadcasting_Company" title="Australian Broadcasting Company">Australian Broadcasting Company</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20131028235508/http://www.abc.net.au/local/stories/2012/06/13/3524011.htm">Archived</a> from the original on October 28, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">June 28,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Living+off+the+grid%3A+American+football+in+coastal+Australia&rft.pub=Australian+Broadcasting+Company&rft.date=2012-06-13&rft.aulast=Huntsdale&rft.aufirst=Justin&rft_id=http%3A%2F%2Fwww.abc.net.au%2Flocal%2Fstories%2F2012%2F06%2F13%2F3524011.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-The_basics_of_rugby_union-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-The_basics_of_rugby_union_9-0">^</a></b></span> <span class="reference-text"><cite class="citation news"><a rel="nofollow" class="external text" href="http://news.bbc.co.uk/sport2/hi/rugby_union/rules_and_equipment/4200680.stm">"The basics of rugby union"</a>. <a href="/wiki/BBC" title="BBC">BBC</a>. September 2005. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140301181407/http://news.bbc.co.uk/sport2/hi/rugby_union/rules_and_equipment/4200680.stm">Archived</a> from the original on March 1, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">April 19,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=The+basics+of+rugby+union&rft.date=2005-09&rft_id=http%3A%2F%2Fnews.bbc.co.uk%2Fsport2%2Fhi%2Frugby_union%2Frules_and_equipment%2F4200680.stm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Rutgers-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-Rutgers_10-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20140924154500/http://www.scarletknights.com/football/history/first-game.asp">"Rutgers – The Birthplace of Intercollegiate Football"</a>. <a href="/wiki/Rutgers_University" title="Rutgers University">Rutgers University</a>. Archived from <a rel="nofollow" class="external text" href="http://scarletknights.com/football/history/first-game.asp">the original</a> on September 24, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">November 24,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Rutgers+%E2%80%93+The+Birthplace+of+Intercollegiate+Football&rft.pub=Rutgers+University&rft_id=http%3A%2F%2Fscarletknights.com%2Ffootball%2Fhistory%2Ffirst-game.asp&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-No_Christian_End-11"><span class="mw-cite-backlink">^ <a href="#cite_ref-No_Christian_End_11-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-No_Christian_End_11-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-No_Christian_End_11-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><cite class="citation journal"><a rel="nofollow" class="external text" href="http://www.profootballresearchers.com/articles/No_Christian_End.pdf">"No Christian End! The Beginnings of Football in America"</a> <span class="cs1-format">(PDF)</span>. <a href="/wiki/Professional_Football_Researchers_Association" title="Professional Football Researchers Association">Professional Football Researchers Association</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150402124846/http://www.profootballresearchers.com/articles/No_Christian_End.pdf">Archived</a> <span class="cs1-format">(PDF)</span> from the original on April 2, 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">November 24,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=No+Christian+End%21+The+Beginnings+of+Football+in+America&rft_id=http%3A%2F%2Fwww.profootballresearchers.com%2Farticles%2FNo_Christian_End.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span> <span class="cs1-hidden-error error citation-comment">Cite journal requires <code class="cs1-code">|journal=</code> (<a href="/wiki/Help:CS1_errors#missing_periodical" title="Help:CS1 errors">help</a>)</span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.rcinet.ca/en/2015/05/14/history-may-14-1874-how-canada-created-american-football/">"History- May 14, 1874 How Canada created American football"</a>. <i>rcinet.ca</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20181009052657/http://www.rcinet.ca/en/2015/05/14/history-may-14-1874-how-canada-created-american-football/">Archived</a> from the original on October 9, 2018<span class="reference-accessdate">. Retrieved <span class="nowrap">October 8,</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=rcinet.ca&rft.atitle=History-+May+14%2C+1874+How+Canada+created+American+football&rft_id=http%3A%2F%2Fwww.rcinet.ca%2Fen%2F2015%2F05%2F14%2Fhistory-may-14-1874-how-canada-created-american-football%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="https://www.mcgill.ca/channels/news/date-history-first-football-game-was-may-14-1874-106694">"This Date in History: First football game was May 14, 1874"</a>. <i>mcgill.ca</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20180629074259/https://www.mcgill.ca/channels/news/date-history-first-football-game-was-may-14-1874-106694">Archived</a> from the original on June 29, 2018<span class="reference-accessdate">. Retrieved <span class="nowrap">October 8,</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=mcgill.ca&rft.atitle=This+Date+in+History%3A+First+football+game+was+May+14%2C+1874&rft_id=https%3A%2F%2Fwww.mcgill.ca%2Fchannels%2Fnews%2Fdate-history-first-football-game-was-may-14-1874-106694&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Camp_and_His_Followers-14"><span class="mw-cite-backlink">^ <a href="#cite_ref-Camp_and_His_Followers_14-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Camp_and_His_Followers_14-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Camp_and_His_Followers_14-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Camp_and_His_Followers_14-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Camp_and_His_Followers_14-4"><sup><i><b>e</b></i></sup></a></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.profootballresearchers.com/articles/Camp_And_Followers.pdf">"Camp and His Followers"</a> <span class="cs1-format">(PDF)</span>. <a href="/wiki/Professional_Football_Researchers_Association" title="Professional Football Researchers Association">Professional Football Researchers Association</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150118174334/http://profootballresearchers.com/articles/Camp_And_Followers.pdf">Archived</a> <span class="cs1-format">(PDF)</span> from the original on January 18, 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">November 24,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Camp+and+His+Followers&rft.pub=Professional+Football+Researchers+Association&rft_id=http%3A%2F%2Fwww.profootballresearchers.com%2Farticles%2FCamp_And_Followers.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-NFL1869-15"><span class="mw-cite-backlink">^ <a href="#cite_ref-NFL1869_15-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NFL1869_15-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.nfl.com/history/chronology/1869-1910#1892">"NFL History 1869–1910"</a>. <a href="/wiki/NFL.com" class="mw-redirect" title="NFL.com">NFL.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080102045951/http://www.nfl.com/history/chronology/1869-1910#1892">Archived</a> from the original on January 2, 2008<span class="reference-accessdate">. Retrieved <span class="nowrap">November 24,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=NFL+History+1869%E2%80%931910&rft.pub=NFL.com&rft_id=http%3A%2F%2Fwww.nfl.com%2Fhistory%2Fchronology%2F1869-1910%231892&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.newenglandhistoricalsociety.com/walter-camp-and-birth-modern-football/">"Walter Camp and the Birth of Modern Football"</a>. New England Historical Society. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20181026064524/http://www.newenglandhistoricalsociety.com/walter-camp-and-birth-modern-football/">Archived</a> from the original on October 26, 2018<span class="reference-accessdate">. Retrieved <span class="nowrap">January 3,</span> 2019</span>. <q>As a senior at Yale, Camp prevailed at Massasoit House and cut the number of players to 11 from 15. That year [1882] he also came up with the idea for a static line of scrimmage.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Walter+Camp+and+the+Birth+of+Modern+Football&rft.pub=New+England+Historical+Society&rft_id=http%3A%2F%2Fwww.newenglandhistoricalsociety.com%2Fwalter-camp-and-birth-modern-football%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text">Bennett (1976), p. 20.</span>
</li>
<li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text"><cite class="citation journal">Lewis, Guy M. (1969). "Teddy Roosevelt's Role in the 1905 Football Controversy". <i>The Research Quarterly</i>. <b>40</b>: 717–724.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Research+Quarterly&rft.atitle=Teddy+Roosevelt%27s+Role+in+the+1905+Football+Controversy&rft.volume=40&rft.pages=717-724&rft.date=1969&rft.aulast=Lewis&rft.aufirst=Guy+M.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
</li>
<li id="cite_note-NCAA-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-NCAA_19-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20070430205324/http://www.ncaa.org/about/history.html">"The History of the NCAA"</a>. <a href="/wiki/National_Collegiate_Athletic_Association" title="National Collegiate Athletic Association">National Collegiate Athletic Association</a>. Archived from <a rel="nofollow" class="external text" href="https://www.ncaa.org/about/history.html">the original</a> on April 30, 2007<span class="reference-accessdate">. Retrieved <span class="nowrap">November 24,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+History+of+the+NCAA&rft.pub=National+Collegiate+Athletic+Association&rft_id=https%3A%2F%2Fwww.ncaa.org%2Fabout%2Fhistory.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-20">^</a></b></span> <span class="reference-text"><cite class="citation news"><a rel="nofollow" class="external text" href="https://www.nytimes.com/2007/09/22/sports/ncaafootball/22harvard.html?_r=0">"Saturday Night Lights: Harvard Stadium Joins the 21st Century"</a>. <i>New York Times</i><span class="reference-accessdate">. Retrieved <span class="nowrap">April 12,</span> 2016</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=New+York+Times&rft.atitle=Saturday+Night+Lights%3A+Harvard+Stadium+Joins+the+21st+Century&rft_id=https%3A%2F%2Fwww.nytimes.com%2F2007%2F09%2F22%2Fsports%2Fncaafootball%2F22harvard.html%3F_r%3D0&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Blondy_Wallace_and_the_Biggest_Football_Scandal_Ever:_1906-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-Blondy_Wallace_and_the_Biggest_Football_Scandal_Ever:_1906_21-0">^</a></b></span> <span class="reference-text"><cite class="citation journal">Braunwart, Bob; Carroll, Bob. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140928221224/http://www.profootballresearchers.org/Coffin_Corner/06-An-209.pdf">"Blondy Wallace and the Biggest Football Scandal Ever: 1906"</a> <span class="cs1-format">(PDF)</span>. <i><a href="/wiki/The_Coffin_Corner" class="mw-redirect" title="The Coffin Corner">The Coffin Corner</a></i>. Archived from <a rel="nofollow" class="external text" href="http://www.profootballresearchers.org/Coffin_Corner/06-An-209.pdf">the original</a> <span class="cs1-format">(PDF)</span> on September 28, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">November 25,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Coffin+Corner&rft.atitle=Blondy+Wallace+and+the+Biggest+Football+Scandal+Ever%3A+1906&rft.aulast=Braunwart&rft.aufirst=Bob&rft.au=Carroll%2C+Bob&rft_id=http%3A%2F%2Fwww.profootballresearchers.org%2FCoffin_Corner%2F06-An-209.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
</li>
<li id="cite_note-NFL1911-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL1911_22-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.nfl.com/history/chronology/1911-1920#1920">"NFL History 1911–1920"</a>. <a href="/wiki/NFL.com" class="mw-redirect" title="NFL.com">NFL.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080115043331/http://www.nfl.com/history/chronology/1911-1920#1920">Archived</a> from the original on January 15, 2008<span class="reference-accessdate">. Retrieved <span class="nowrap">November 24,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=NFL+History+1911%E2%80%931920&rft.pub=NFL.com&rft_id=http%3A%2F%2Fwww.nfl.com%2Fhistory%2Fchronology%2F1911-1920%231920&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Danzig1956-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-Danzig1956_23-0">^</a></b></span> <span class="reference-text"><cite class="citation book">Danzig, Allison (1956). <span class="cs1-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/historyofamerica00danz"><i>The History of American Football: Its Great Teams, Players, and Coaches</i></a></span>. Englewood Cliffs, N.J.: <a href="/wiki/Prentice_Hall" title="Prentice Hall">Prentice Hall</a>. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/historyofamerica00danz/page/70">70–71</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+History+of+American+Football%3A+Its+Great+Teams%2C+Players%2C+and+Coaches&rft.place=Englewood+Cliffs%2C+N.J.&rft.pages=70-71&rft.pub=Prentice+Hall&rft.date=1956&rft.aulast=Danzig&rft.aufirst=Allison&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fhistoryofamerica00danz&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text">Vancil (2000), p. 22.</span>
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<li id="cite_note-birth-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-birth_25-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20061116215456/http://www.profootballhof.com/history/general/birth.jsp">"The Birth of Pro Football"</a>. <a href="/wiki/Pro_Football_Hall_of_Fame" title="Pro Football Hall of Fame">Pro Football Hall of Fame</a>. Archived from <a rel="nofollow" class="external text" href="http://www.profootballhof.com/history/general/birth.jsp">the original</a> on November 16, 2006<span class="reference-accessdate">. Retrieved <span class="nowrap">March 19,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+Birth+of+Pro+Football&rft.pub=Pro+Football+Hall+of+Fame&rft_id=http%3A%2F%2Fwww.profootballhof.com%2Fhistory%2Fgeneral%2Fbirth.jsp&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-The_First_25_Years-26"><span class="mw-cite-backlink">^ <a href="#cite_ref-The_First_25_Years_26-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-The_First_25_Years_26-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite class="citation journal">Clary, Jack (1994). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140928221312/http://www.profootballresearchers.org/Coffin_Corner/16-04-570.pdf">"The First 25 Years"</a> <span class="cs1-format">(PDF)</span>. <i><a href="/wiki/The_Coffin_Corner" class="mw-redirect" title="The Coffin Corner">The Coffin Corner</a></i>. <b>16</b> (4): 1, 4–5. Archived from <a rel="nofollow" class="external text" href="http://www.profootballresearchers.org/Coffin_Corner/16-04-570.pdf">the original</a> <span class="cs1-format">(PDF)</span> on September 28, 2014.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Coffin+Corner&rft.atitle=The+First+25+Years&rft.volume=16&rft.issue=4&rft.pages=1%2C+4-5&rft.date=1994&rft.aulast=Clary&rft.aufirst=Jack&rft_id=http%3A%2F%2Fwww.profootballresearchers.org%2FCoffin_Corner%2F16-04-570.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text">Jozsa (2004), pp. 270.</span>
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<li id="cite_note-The_Curse-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-The_Curse_28-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Nelson, Robert (January 11, 2007). <a rel="nofollow" class="external text" href="http://www.phoenixnewtimes.com/2007-01-11/news/the-curse/full">"The Curse"</a>. <i><a href="/wiki/Phoenix_New_Times" title="Phoenix New Times">Phoenix New Times</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20131019055036/http://www.phoenixnewtimes.com/2007-01-11/news/the-curse/full">Archived</a> from the original on October 19, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">January 30,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Phoenix+New+Times&rft.atitle=The+Curse&rft.date=2007-01-11&rft.aulast=Nelson&rft.aufirst=Robert&rft_id=http%3A%2F%2Fwww.phoenixnewtimes.com%2F2007-01-11%2Fnews%2Fthe-curse%2Ffull&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Greatest_game_ever_played-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-Greatest_game_ever_played_29-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.profootballhof.com/history/release.aspx?release_id=1805">"Greatest game ever played"</a>. <a href="/wiki/Pro_Football_Hall_of_Fame" title="Pro Football Hall of Fame">Pro Football Hall of Fame</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130515154221/http://www.profootballhof.com/history/release.aspx?release_id=1805">Archived</a> from the original on May 15, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">March 20,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Greatest+game+ever+played&rft.pub=Pro+Football+Hall+of+Fame&rft_id=http%3A%2F%2Fwww.profootballhof.com%2Fhistory%2Frelease.aspx%3Frelease_id%3D1805&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-inflation-USGDP-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-inflation-USGDP_30-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Thomas, Ryland; Williamson, Samuel H. (2019). <a rel="nofollow" class="external text" href="http://www.measuringworth.com/datasets/usgdp/">"What Was the U.S. GDP Then?"</a>. <i>MeasuringWorth</i><span class="reference-accessdate">. Retrieved <span class="nowrap">April 6,</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=MeasuringWorth&rft.atitle=What+Was+the+U.S.+GDP+Then%3F&rft.date=2019&rft.aulast=Thomas&rft.aufirst=Ryland&rft.au=Williamson%2C+Samuel+H.&rft_id=http%3A%2F%2Fwww.measuringworth.com%2Fdatasets%2Fusgdp%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"> United States <a href="/wiki/Gross_Domestic_Product_deflator" class="mw-redirect" title="Gross Domestic Product deflator">Gross Domestic Product deflator</a> figures follow the <i>Measuring Worth</i> series. </span>
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<li id="cite_note-The_Second_25_Years-31"><span class="mw-cite-backlink">^ <a href="#cite_ref-The_Second_25_Years_31-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-The_Second_25_Years_31-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite class="citation journal">Clary, Jack (1994). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20141019125833/http://www.profootballresearchers.org/Coffin_Corner/16-05-575.pdf">"The Second 25 Years"</a> <span class="cs1-format">(PDF)</span>. <i><a href="/wiki/The_Coffin_Corner" class="mw-redirect" title="The Coffin Corner">The Coffin Corner</a></i>. <b>16</b> (5): 4–5. Archived from <a rel="nofollow" class="external text" href="http://www.profootballresearchers.org/Coffin_Corner/16-05-575.pdf">the original</a> <span class="cs1-format">(PDF)</span> on October 19, 2014.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Coffin+Corner&rft.atitle=The+Second+25+Years&rft.volume=16&rft.issue=5&rft.pages=4-5&rft.date=1994&rft.aulast=Clary&rft.aufirst=Jack&rft_id=http%3A%2F%2Fwww.profootballresearchers.org%2FCoffin_Corner%2F16-05-575.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-BCS-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-BCS_32-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20100113132437/http://www.bcsfootball.org/bcsfb/history">"BCS Chronology"</a>. <i>bcsfootball.org</i>. FOX Sports on MSN. 2006. Archived from <a rel="nofollow" class="external text" href="http://www.bcsfootball.org/bcsfb/history">the original</a> on January 13, 2010<span class="reference-accessdate">. Retrieved <span class="nowrap">March 19,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=bcsfootball.org&rft.atitle=BCS+Chronology&rft.date=2006&rft_id=http%3A%2F%2Fwww.bcsfootball.org%2Fbcsfb%2Fhistory&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
</li>
<li id="cite_note-Presidents_get_playoff_plan_right-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-Presidents_get_playoff_plan_right_33-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a href="/wiki/Gene_Wojciechowski" title="Gene Wojciechowski">Wojciechowski, Jean</a> (June 26, 2012). <a rel="nofollow" class="external text" href="http://espn.go.com/college-football/story/_/id/8099205/college-football-time-celebrate-approval-four-team-playoff">"Presidents get playoff plan right"</a>. <a href="/wiki/ESPN.com" title="ESPN.com">ESPN.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130523003316/http://espn.go.com/college-football/story/_/id/8099205/college-football-time-celebrate-approval-four-team-playoff">Archived</a> from the original on May 23, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">March 20,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Presidents+get+playoff+plan+right&rft.pub=ESPN.com&rft.date=2012-06-26&rft.au=Wojciechowski%2C+Jean&rft_id=http%3A%2F%2Fespn.go.com%2Fcollege-football%2Fstory%2F_%2Fid%2F8099205%2Fcollege-football-time-celebrate-approval-four-team-playoff&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-34">^</a></b></span> <span class="reference-text"><cite class="citation web">Russo, Ralph D. (January 2, 2015). <a rel="nofollow" class="external text" href="https://www.thestar.com/sports/football/2015/01/02/ncaa_college_football_playoff_pits_powerhouses_ohio_state_and_oregon.html">"NCAA College Football Playoff pits powerhouses Ohio State and Oregon"</a>. <i><a href="/wiki/Toronto_Star" title="Toronto Star">Toronto Star</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150106094442/http://www.thestar.com/sports/football/2015/01/02/ncaa_college_football_playoff_pits_powerhouses_ohio_state_and_oregon.html">Archived</a> from the original on January 6, 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">January 16,</span> 2015</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Toronto+Star&rft.atitle=NCAA+College+Football+Playoff+pits+powerhouses+Ohio+State+and+Oregon&rft.date=2015-01-02&rft.aulast=Russo&rft.aufirst=Ralph+D.&rft_id=https%3A%2F%2Fwww.thestar.com%2Fsports%2Ffootball%2F2015%2F01%2F02%2Fncaa_college_football_playoff_pits_powerhouses_ohio_state_and_oregon.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
</li>
<li id="cite_note-NFL_Rules_2012,_p._21-35"><span class="mw-cite-backlink">^ <a href="#cite_ref-NFL_Rules_2012,_p._21_35-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NFL_Rules_2012,_p._21_35-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-NFL_Rules_2012,_p._21_35-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">NFL Rules 2012, p. 21.</span>
</li>
<li id="cite_note-NCAA_Rules_2011–2012,_p._15-36"><span class="mw-cite-backlink">^ <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._15_36-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._15_36-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NCAA Rules 2011–2012, p. 15.</span>
</li>
<li id="cite_note-NFHS_Rules_2012,_p._11-37"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_p._11_37-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, p. 11.</span>
</li>
<li id="cite_note-NCAA_Rules_2011–2012,_p._107-38"><span class="mw-cite-backlink"><b><a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._107_38-0">^</a></b></span> <span class="reference-text">NCAA Rules 2011–2012, p. 107.</span>
</li>
<li id="cite_note-NFHS_Rules_2012,_pp._71-72-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_pp._71-72_39-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, pp. 71–72.</span>
</li>
<li id="cite_note-NFL_Rules_2012,_pp._21-22-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_Rules_2012,_pp._21-22_40-0">^</a></b></span> <span class="reference-text">NFL Rules 2012, pp. 21–22.</span>
</li>
<li id="cite_note-NCAA_Rules_2011–2012,_pp._53-54-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_pp._53-54_41-0">^</a></b></span> <span class="reference-text">NCAA Rules 2011–2012, pp. 53–54.</span>
</li>
<li id="cite_note-NFHS_Rules_2012,_pp._45-46-42"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_pp._45-46_42-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, pp. 45–46.</span>
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<li id="cite_note-The_innovator-43"><span class="mw-cite-backlink"><b><a href="#cite_ref-The_innovator_43-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Dickson, James David (July 14, 2010). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20131019065323/http://michigantoday.umich.edu/2010/07/story.php?id=7795">"The innovator"</a>. <a href="/wiki/Michigan_Today" class="mw-redirect" title="Michigan Today">Michigan Today</a>. Archived from <a rel="nofollow" class="external text" href="http://michigantoday.umich.edu/2010/07/story.php?id=7795">the original</a> on October 19, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">October 7,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+innovator&rft.pub=Michigan+Today&rft.date=2010-07-14&rft.aulast=Dickson&rft.aufirst=James+David&rft_id=http%3A%2F%2Fmichigantoday.umich.edu%2F2010%2F07%2Fstory.php%3Fid%3D7795&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-NCAA_Rules_2011–2012,_pp._21-22-44"><span class="mw-cite-backlink"><b><a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_pp._21-22_44-0">^</a></b></span> <span class="reference-text">NCAA Rules 2011–2012, pp. 21–22.</span>
</li>
<li id="cite_note-NFHS_Rules_2012,_pp._16-17-45"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_pp._16-17_45-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, pp. 16–17.</span>
</li>
<li id="cite_note-For_women,_tackling_NFL_is_a_long_shot-46"><span class="mw-cite-backlink"><b><a href="#cite_ref-For_women,_tackling_NFL_is_a_long_shot_46-0">^</a></b></span> <span class="reference-text"><cite class="citation web">McManus, Jane (May 11, 2011). <a rel="nofollow" class="external text" href="http://www.espn.com/espnw/news/article/6516042/women-pros-women-tackling-nfl-long-shot">"For women, tackling NFL is a long shot"</a>. <a href="/wiki/ESPN.com#ESPNW" title="ESPN.com">ESPNW</a><span class="reference-accessdate">. Retrieved <span class="nowrap">August 10,</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=For+women%2C+tackling+NFL+is+a+long+shot&rft.pub=ESPNW&rft.date=2011-05-11&rft.aulast=McManus&rft.aufirst=Jane&rft_id=http%3A%2F%2Fwww.espn.com%2Fespnw%2Fnews%2Farticle%2F6516042%2Fwomen-pros-women-tackling-nfl-long-shot&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-More_Girls_Are_Playing_Football-47"><span class="mw-cite-backlink"><b><a href="#cite_ref-More_Girls_Are_Playing_Football_47-0">^</a></b></span> <span class="reference-text"><cite class="citation web">de la Cretaz, Britni (February 2, 2018). <a rel="nofollow" class="external text" href="https://www.nytimes.com/2018/02/02/well/family/football-girls-concussions.html">"More Girls Are Playing Football. Is That Progress?"</a>. <i><a href="/wiki/The_New_York_Times" title="The New York Times">The New York Times</a></i><span class="reference-accessdate">. Retrieved <span class="nowrap">August 10,</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+New+York+Times&rft.atitle=More+Girls+Are+Playing+Football.+Is+That+Progress%3F&rft.date=2018-02-02&rft.aulast=de+la+Cretaz&rft.aufirst=Britni&rft_id=https%3A%2F%2Fwww.nytimes.com%2F2018%2F02%2F02%2Fwell%2Ffamily%2Ffootball-girls-concussions.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-48"><span class="mw-cite-backlink"><b><a href="#cite_ref-48">^</a></b></span> <span class="reference-text"><cite class="citation web">Fox, Ashley (April 17, 2015). <a rel="nofollow" class="external text" href="https://www.espn.com/nfl/story/_/id/12669370/meet-sarah-thomas-first-female-nfl-official-referee">"Meet Sarah Thomas, NFL's first female official"</a>. <a href="/wiki/ESPN.com" title="ESPN.com">ESPN.com</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Meet+Sarah+Thomas%2C+NFL%27s+first+female+official&rft.pub=ESPN.com&rft.date=2015-04-17&rft.aulast=Fox&rft.aufirst=Ashley&rft_id=https%3A%2F%2Fwww.espn.com%2Fnfl%2Fstory%2F_%2Fid%2F12669370%2Fmeet-sarah-thomas-first-female-nfl-official-referee&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-NFL_in_a_nutshell-49"><span class="mw-cite-backlink">^ <a href="#cite_ref-NFL_in_a_nutshell_49-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NFL_in_a_nutshell_49-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-NFL_in_a_nutshell_49-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-NFL_in_a_nutshell_49-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-NFL_in_a_nutshell_49-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-NFL_in_a_nutshell_49-5"><sup><i><b>f</b></i></sup></a></span> <span class="reference-text"><cite class="citation news"><a rel="nofollow" class="external text" href="http://news.bbc.co.uk/sport2/hi/other_sports/american_football/3192002.stm">"NFL in a nutshell"</a>. <i>BBC Sport</i>. October 19, 2005. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20121122215916/http://news.bbc.co.uk/sport2/hi/other_sports/american_football/3192002.stm">Archived</a> from the original on November 22, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">November 20,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=BBC+Sport&rft.atitle=NFL+in+a+nutshell&rft.date=2005-10-19&rft_id=http%3A%2F%2Fnews.bbc.co.uk%2Fsport2%2Fhi%2Fother_sports%2Famerican_football%2F3192002.stm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-NFL_Rules_2012,_pp._21-24-50"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_Rules_2012,_pp._21-24_50-0">^</a></b></span> <span class="reference-text">NFL Rules 2012, pp. 21–24.</span>
</li>
<li id="cite_note-NFHS_Rules_2012,_pp._57-58-51"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_pp._57-58_51-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, pp. 57–58.</span>
</li>
<li id="cite_note-NFL_Rules_2012,_pp._36,_40-52"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_Rules_2012,_pp._36,_40_52-0">^</a></b></span> <span class="reference-text">NFL Rules 2012, pp. 36, 40.</span>
</li>
<li id="cite_note-Common_Penalties_in_American_Football-53"><span class="mw-cite-backlink"><b><a href="#cite_ref-Common_Penalties_in_American_Football_53-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a href="/wiki/Howie_Long" title="Howie Long">Long, Howie</a>; Czarnecki, John. <a rel="nofollow" class="external text" href="http://www.dummies.com/how-to/content/common-penalties-in-american-football.html">"Common Penalties in American Football"</a>. <a href="/wiki/For_Dummies" title="For Dummies">Dummies.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20121223110721/http://www.dummies.com/how-to/content/common-penalties-in-american-football.html">Archived</a> from the original on December 23, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">November 23,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Common+Penalties+in+American+Football&rft.pub=Dummies.com&rft.aulast=Long&rft.aufirst=Howie&rft.au=Czarnecki%2C+John&rft_id=http%3A%2F%2Fwww.dummies.com%2Fhow-to%2Fcontent%2Fcommon-penalties-in-american-football.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Football_Players'_Roles_in_Team_Offense_and_Defense-54"><span class="mw-cite-backlink">^ <a href="#cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-Football_Players'_Roles_in_Team_Offense_and_Defense_54-7"><sup><i><b>h</b></i></sup></a></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.dummies.com/how-to/content/football-players-roles-in-team-offense-and-defense.html">"Football Players' Roles in Team Offense and Defense"</a>. <a href="/wiki/For_Dummies" title="For Dummies">Dummies.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130106181746/http://www.dummies.com/how-to/content/football-players-roles-in-team-offense-and-defense.html">Archived</a> from the original on January 6, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">January 14,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Football+Players%27+Roles+in+Team+Offense+and+Defense&rft.pub=Dummies.com&rft_id=http%3A%2F%2Fwww.dummies.com%2Fhow-to%2Fcontent%2Ffootball-players-roles-in-team-offense-and-defense.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Fullbacks_back_en_vogue-55"><span class="mw-cite-backlink"><b><a href="#cite_ref-Fullbacks_back_en_vogue_55-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Pasquarelli, Len (June 1, 2010). <a rel="nofollow" class="external text" href="http://sports.espn.go.com/nfl/columns/story?columnist=pasquarelli_len&id=5238185">"Fullbacks back en vogue"</a>. <a href="/wiki/ESPN.com" title="ESPN.com">ESPN.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140725082524/http://sports.espn.go.com/nfl/columns/story?columnist=pasquarelli_len&id=5238185">Archived</a> from the original on July 25, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">November 22,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Fullbacks+back+en+vogue&rft.pub=ESPN.com&rft.date=2010-06-01&rft.aulast=Pasquarelli&rft.aufirst=Len&rft_id=http%3A%2F%2Fsports.espn.go.com%2Fnfl%2Fcolumns%2Fstory%3Fcolumnist%3Dpasquarelli_len%26id%3D5238185&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Centers:_The_Unsung_Heroes_of_Football-56"><span class="mw-cite-backlink"><b><a href="#cite_ref-Centers:_The_Unsung_Heroes_of_Football_56-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Wood, Ryan (October 23, 2009). <a rel="nofollow" class="external text" href="http://www.active.com/football/Articles/Centers-The-Unsung-Heroes-of-Football">"Centers: The Unsung Heroes of Football"</a>. Active.com. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130530052506/http://www.active.com/football/Articles/Centers-The-Unsung-Heroes-of-Football">Archived</a> from the original on May 30, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">November 22,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Centers%3A+The+Unsung+Heroes+of+Football&rft.pub=Active.com&rft.date=2009-10-23&rft.aulast=Wood&rft.aufirst=Ryan&rft_id=http%3A%2F%2Fwww.active.com%2Ffootball%2FArticles%2FCenters-The-Unsung-Heroes-of-Football&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Football's_Offensive_Team:_The_Receivers-57"><span class="mw-cite-backlink"><b><a href="#cite_ref-Football's_Offensive_Team:_The_Receivers_57-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a href="/wiki/Howie_Long" title="Howie Long">Long, Howie</a>; Czarnecki, John. <a rel="nofollow" class="external text" href="http://www.dummies.com/how-to/content/footballs-offensive-team-the-receivers.html">"Football's Offensive Team: The Receivers"</a>. <a href="/wiki/For_Dummies" title="For Dummies">Dummies.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130303005856/http://www.dummies.com/how-to/content/footballs-offensive-team-the-receivers.html">Archived</a> from the original on March 3, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">November 22,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Football%27s+Offensive+Team%3A+The+Receivers&rft.pub=Dummies.com&rft.aulast=Long&rft.aufirst=Howie&rft.au=Czarnecki%2C+John&rft_id=http%3A%2F%2Fwww.dummies.com%2Fhow-to%2Fcontent%2Ffootballs-offensive-team-the-receivers.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Football's_Defensive_Team:_The_Linebackers-58"><span class="mw-cite-backlink"><b><a href="#cite_ref-Football's_Defensive_Team:_The_Linebackers_58-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a href="/wiki/Howie_Long" title="Howie Long">Long, Howie</a>; Czarnecki, John. <a rel="nofollow" class="external text" href="http://www.dummies.com/how-to/content/footballs-defense-team-the-linebackers.html">"Football's Defensive Team: The Linebackers"</a>. <a href="/wiki/For_Dummies" title="For Dummies">Dummies.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130122084614/http://www.dummies.com/how-to/content/footballs-defense-team-the-linebackers.html">Archived</a> from the original on January 22, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">November 23,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Football%27s+Defensive+Team%3A+The+Linebackers&rft.pub=Dummies.com&rft.aulast=Long&rft.aufirst=Howie&rft.au=Czarnecki%2C+John&rft_id=http%3A%2F%2Fwww.dummies.com%2Fhow-to%2Fcontent%2Ffootballs-defense-team-the-linebackers.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-The_Role_of_Special_Teams_in_a_Football_Game-59"><span class="mw-cite-backlink"><b><a href="#cite_ref-The_Role_of_Special_Teams_in_a_Football_Game_59-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a href="/wiki/Howie_Long" title="Howie Long">Long, Howie</a>; Czarnecki, John. <a rel="nofollow" class="external text" href="http://www.dummies.com/how-to/content/the-role-of-special-teams-in-a-football-game.html">"The Role of Special Teams in a Football Game"</a>. <a href="/wiki/For_Dummies" title="For Dummies">Dummies.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20120124014652/http://www.dummies.com/how-to/content/the-role-of-special-teams-in-a-football-game.html">Archived</a> from the original on January 24, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">January 12,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+Role+of+Special+Teams+in+a+Football+Game&rft.pub=Dummies.com&rft.aulast=Long&rft.aufirst=Howie&rft.au=Czarnecki%2C+John&rft_id=http%3A%2F%2Fwww.dummies.com%2Fhow-to%2Fcontent%2Fthe-role-of-special-teams-in-a-football-game.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Football_Special_Teams:_Players_on_a_Punt_Team-60"><span class="mw-cite-backlink"><b><a href="#cite_ref-Football_Special_Teams:_Players_on_a_Punt_Team_60-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a href="/wiki/Howie_Long" title="Howie Long">Long, Howie</a>; Czarnecki, John. <a rel="nofollow" class="external text" href="http://www.dummies.com/how-to/content/football-special-teams-players-on-a-punt-team.html">"Football Special Teams: Players on a Punt Team"</a>. <a href="/wiki/For_Dummies" title="For Dummies">Dummies.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20120126113938/http://www.dummies.com/how-to/content/football-special-teams-players-on-a-punt-team.html">Archived</a> from the original on January 26, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">January 12,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Football+Special+Teams%3A+Players+on+a+Punt+Team&rft.pub=Dummies.com&rft.aulast=Long&rft.aufirst=Howie&rft.au=Czarnecki%2C+John&rft_id=http%3A%2F%2Fwww.dummies.com%2Fhow-to%2Fcontent%2Ffootball-special-teams-players-on-a-punt-team.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Duke-61"><span class="mw-cite-backlink"><b><a href="#cite_ref-Duke_61-0">^</a></b></span> <span class="reference-text"><cite class="citation journal">Sackrowitz, Harold (2000). <a rel="nofollow" class="external text" href="http://www.stat.duke.edu/~dalene/chance/chanceweb/133.sackrowitz.pdf">"Refining the Point(s)-After-Touchdown Decision"</a> <span class="cs1-format">(PDF)</span>. <i>Department of Statistical Science</i>. <b>13</b> (3): 29–30, 33–34. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20131002214621/http://www.stat.duke.edu/~dalene/chance/chanceweb/133.sackrowitz.pdf">Archived</a> <span class="cs1-format">(PDF)</span> from the original on October 2, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">October 23,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Department+of+Statistical+Science&rft.atitle=Refining+the+Point%28s%29-After-Touchdown+Decision&rft.volume=13&rft.issue=3&rft.pages=29-30%2C+33-34&rft.date=2000&rft.aulast=Sackrowitz&rft.aufirst=Harold&rft_id=http%3A%2F%2Fwww.stat.duke.edu%2F~dalene%2Fchance%2Fchanceweb%2F133.sackrowitz.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-NFL_Rules_2012,_p._57-59-62"><span class="mw-cite-backlink">^ <a href="#cite_ref-NFL_Rules_2012,_p._57-59_62-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NFL_Rules_2012,_p._57-59_62-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NFL Rules 2012, pp. 57–59.</span>
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<li id="cite_note-NCAA_Rules_2011–2012,_p._79-80-63"><span class="mw-cite-backlink">^ <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._79-80_63-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._79-80_63-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NCAA Rules 2011–2012, pp. 79–80.</span>
</li>
<li id="cite_note-NFHS_Rules_2012,_p._66-64"><span class="mw-cite-backlink">^ <a href="#cite_ref-NFHS_Rules_2012,_p._66_64-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NFHS_Rules_2012,_p._66_64-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NFHS Rules 2012, p. 66.</span>
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<li id="cite_note-Beginner's_Guide_to_Football-65"><span class="mw-cite-backlink">^ <a href="#cite_ref-Beginner's_Guide_to_Football_65-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Beginner's_Guide_to_Football_65-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Beginner's_Guide_to_Football_65-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.nfl.com/rulebook/beginnersguidetofootball">"Beginner's Guide to Football"</a>. <a href="/wiki/National_Football_League" title="National Football League">National Football League</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110216225503/http://www.nfl.com/rulebook/beginnersguidetofootball">Archived</a> from the original on February 16, 2011<span class="reference-accessdate">. Retrieved <span class="nowrap">September 30,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Beginner%27s+Guide+to+Football&rft.pub=National+Football+League&rft_id=http%3A%2F%2Fwww.nfl.com%2Frulebook%2Fbeginnersguidetofootball&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-NFL_Rules_2012,_p._60-66"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_Rules_2012,_p._60_66-0">^</a></b></span> <span class="reference-text">NFL Rules 2012, p. 60</span>
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<li id="cite_note-NFL_Rules_2012,_p._v,_1-67"><span class="mw-cite-backlink">^ <a href="#cite_ref-NFL_Rules_2012,_p._v,_1_67-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NFL_Rules_2012,_p._v,_1_67-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NFL Rules 2012, p. v, 1.</span>
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<li id="cite_note-NCAA_Rules_2011–2012,_pp._18-19,_23–24-68"><span class="mw-cite-backlink">^ <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_pp._18-19,_23%E2%80%9324_68-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_pp._18-19,_23%E2%80%9324_68-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NCAA Rules 2011–2012, pp. 18–19, 23–24.</span>
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<li id="cite_note-NFHS_Rules_2012,_pp._11-12,_13,_28-69"><span class="mw-cite-backlink">^ <a href="#cite_ref-NFHS_Rules_2012,_pp._11-12,_13,_28_69-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NFHS_Rules_2012,_pp._11-12,_13,_28_69-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NFHS Rules 2012, pp. 11–12, 13, 28.</span>
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<li id="cite_note-NFL_Rules_2012,_p._2-70"><span class="mw-cite-backlink">^ <a href="#cite_ref-NFL_Rules_2012,_p._2_70-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NFL_Rules_2012,_p._2_70-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NFL Rules 2012, p.  2.</span>
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<li id="cite_note-NCAA_Rules_2011–2012,_p._18-71"><span class="mw-cite-backlink">^ <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._18_71-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._18_71-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NCAA Rules 2011–2012, p. 18.</span>
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<li id="cite_note-NFHS_Rules_2012,_p._14-15-72"><span class="mw-cite-backlink">^ <a href="#cite_ref-NFHS_Rules_2012,_p._14-15_72-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NFHS_Rules_2012,_p._14-15_72-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-NFHS_Rules_2012,_p._14-15_72-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-NFHS_Rules_2012,_p._14-15_72-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text">NFHS Rules 2012, p. 14.</span>
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<li id="cite_note-Bounce_of_an_oval_shaped_football-73"><span class="mw-cite-backlink"><b><a href="#cite_ref-Bounce_of_an_oval_shaped_football_73-0">^</a></b></span> <span class="reference-text"><cite class="citation journal">Cross, Rod (August 2010). <a rel="nofollow" class="external text" href="https://www.researchgate.net/publication/233184599">"Bounce of an oval shaped football"</a>. <i>Sports Technology</i>. <b>3</b> (3): 168–180. <a href="/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1080%2F19346182.2011.564283">10.1080/19346182.2011.564283</a><span class="reference-accessdate">. Retrieved <span class="nowrap">April 23,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Sports+Technology&rft.atitle=Bounce+of+an+oval+shaped+football&rft.volume=3&rft.issue=3&rft.pages=168-180&rft.date=2010-08&rft_id=info%3Adoi%2F10.1080%2F19346182.2011.564283&rft.aulast=Cross&rft.aufirst=Rod&rft_id=https%3A%2F%2Fwww.researchgate.net%2Fpublication%2F233184599&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-NCAA_Rules_2011–2012,_p._20-74"><span class="mw-cite-backlink">^ <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._20_74-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._20_74-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NCAA Rules 2011–2012, p. 20.</span>
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<li id="cite_note-NFL_Rules_2012,_p._3-75"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_Rules_2012,_p._3_75-0">^</a></b></span> <span class="reference-text">NFL Rules 2012, p. 3.</span>
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<li id="cite_note-76"><span class="mw-cite-backlink"><b><a href="#cite_ref-76">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20160303235622/http://uaasnfl.blob.core.windows.net/live/1807/2015_nfl_rule_book_final.pdf">"Official Playing Rules of the National Football League"</a> <span class="cs1-format">(PDF)</span>. Archived from <a rel="nofollow" class="external text" href="http://uaasnfl.blob.core.windows.net/live/1807/2015_nfl_rule_book_final.pdf">the original</a> <span class="cs1-format">(PDF)</span> on March 3, 2016.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Official+Playing+Rules+of+the+National+Football+League&rft_id=http%3A%2F%2Fuaasnfl.blob.core.windows.net%2Flive%2F1807%2F2015_nfl_rule_book_final.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608">, p.3</span>
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<li id="cite_note-NFL_Rules_2012,_p._14-77"><span class="mw-cite-backlink">^ <a href="#cite_ref-NFL_Rules_2012,_p._14_77-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NFL_Rules_2012,_p._14_77-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-NFL_Rules_2012,_p._14_77-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">NFL Rules 2012, p. 14.</span>
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<li id="cite_note-NCAA_Rules_2011–2012,_p._45-78"><span class="mw-cite-backlink">^ <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._45_78-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._45_78-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NCAA Rules 2011–2012, p. 45.</span>
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<li id="cite_note-NFHS_Rules_2012,_pp._38-39-79"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_pp._38-39_79-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, pp. 38–39.</span>
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<li id="cite_note-NFHS_Rules_2012,_p._39-80"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_p._39_80-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, p. 39.</span>
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<li id="cite_note-TMQ's_all-haiku_NFL_preview-81"><span class="mw-cite-backlink"><b><a href="#cite_ref-TMQ's_all-haiku_NFL_preview_81-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a href="/wiki/Gregg_Easterbrook" title="Gregg Easterbrook">Easterbrook, Gregg</a> (September 4, 2008). <a rel="nofollow" class="external text" href="http://sports.espn.go.com/espn/page2/story?page=easterbrook/080902">"TMQ's all-haiku NFL preview"</a>. <a href="/wiki/ESPN.com" title="ESPN.com">ESPN.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20131012030031/http://sports.espn.go.com/espn/page2/story?page=easterbrook%2F080902">Archived</a> from the original on October 12, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">October 1,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=TMQ%27s+all-haiku+NFL+preview&rft.pub=ESPN.com&rft.date=2008-09-04&rft.au=Easterbrook%2C+Gregg&rft_id=http%3A%2F%2Fsports.espn.go.com%2Fespn%2Fpage2%2Fstory%3Fpage%3Deasterbrook%2F080902&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-How_Football_Game_Time_Is_Measured_in_Quarters-82"><span class="mw-cite-backlink"><b><a href="#cite_ref-How_Football_Game_Time_Is_Measured_in_Quarters_82-0">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.dummies.com/how-to/content/how-football-game-time-is-measured-in-quarters.html">"How Football Game Time Is Measured in Quarters"</a>. <a href="/wiki/For_Dummies" title="For Dummies">Dummies.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20121126053220/http://www.dummies.com/how-to/content/how-football-game-time-is-measured-in-quarters.html">Archived</a> from the original on November 26, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">December 2,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=How+Football+Game+Time+Is+Measured+in+Quarters&rft.pub=Dummies.com&rft_id=http%3A%2F%2Fwww.dummies.com%2Fhow-to%2Fcontent%2Fhow-football-game-time-is-measured-in-quarters.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-NFL_Rules_2012,_p._14-18-83"><span class="mw-cite-backlink">^ <a href="#cite_ref-NFL_Rules_2012,_p._14-18_83-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NFL_Rules_2012,_p._14-18_83-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NFL Rules 2012, pp. 14–18</span>
</li>
<li id="cite_note-NCAA_Rules_2011–2012,_pp._47-53-84"><span class="mw-cite-backlink"><b><a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_pp._47-53_84-0">^</a></b></span> <span class="reference-text">NCAA Rules 2011–2012, pp. 47–53.</span>
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<li id="cite_note-NFHS_Rules_2012,_pp._38-45-85"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_pp._38-45_85-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, pp. 38–45</span>
</li>
<li id="cite_note-USA_Today-86"><span class="mw-cite-backlink"><b><a href="#cite_ref-USA_Today_86-0">^</a></b></span> <span class="reference-text"><cite class="citation web">McCarthy, Michael (October 27, 2011). <a rel="nofollow" class="external text" href="http://content.usatoday.com/communities/gameon/post/2011/10/delay-of-game-nfl-games-taking-longer-in-2011-espn-chris-mortensen-dan-masonson/1">"Delay of game: NFL games running longer in 2011"</a>. <i><a href="/wiki/USA_Today" title="USA Today">USA Today</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130707152325/http://content.usatoday.com/communities/gameon/post/2011/10/delay-of-game-nfl-games-taking-longer-in-2011-espn-chris-mortensen-dan-masonson/1">Archived</a> from the original on July 7, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">December 3,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=USA+Today&rft.atitle=Delay+of+game%3A+NFL+games+running+longer+in+2011&rft.date=2011-10-27&rft.aulast=McCarthy&rft.aufirst=Michael&rft_id=http%3A%2F%2Fcontent.usatoday.com%2Fcommunities%2Fgameon%2Fpost%2F2011%2F10%2Fdelay-of-game-nfl-games-taking-longer-in-2011-espn-chris-mortensen-dan-masonson%2F1&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-NCAA_Rules_2011–2012,_pp._16,_41-87"><span class="mw-cite-backlink"><b><a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_pp._16,_41_87-0">^</a></b></span> <span class="reference-text">NCAA Rules 2011–2012, pp. 16, 41.</span>
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<li id="cite_note-NCAA_Rules_2011–2012,_pp._41,_46–47-88"><span class="mw-cite-backlink"><b><a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_pp._41,_46%E2%80%9347_88-0">^</a></b></span> <span class="reference-text">NCAA Rules 2011–2012, pp. 41, 46–47.</span>
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<li id="cite_note-NFHS_Rules_2019-89"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2019_89-0">^</a></b></span> <span class="reference-text">NFHS Rules 2019.</span>
</li>
<li id="cite_note-90"><span class="mw-cite-backlink"><b><a href="#cite_ref-90">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20170123203428/http://www.nfl.com/rulebook/backwardpass">"Backward pass"</a>. <a href="/wiki/National_Football_League" title="National Football League">National Football League</a>. Archived from <a rel="nofollow" class="external text" href="http://www.nfl.com/rulebook/backwardpass">the original</a> on January 23, 2017.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Backward+pass&rft.pub=National+Football+League&rft_id=http%3A%2F%2Fwww.nfl.com%2Frulebook%2Fbackwardpass&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-When_a_runner's_helmet_comes_off,_he's_down-91"><span class="mw-cite-backlink"><b><a href="#cite_ref-When_a_runner's_helmet_comes_off,_he's_down_91-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Smith, Michael David (November 16, 2013). <a rel="nofollow" class="external text" href="http://profootballtalk.nbcsports.com/2013/11/16/when-a-runners-helmet-comes-off-hes-down/">"When a runner's helmet comes off, he's down"</a>. <a href="/wiki/Profootballtalk.com" title="Profootballtalk.com">Profootballtalk.com</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20141019035720/http://profootballtalk.nbcsports.com/2013/11/16/when-a-runners-helmet-comes-off-hes-down/">Archived</a> from the original on October 19, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">October 19,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=When+a+runner%27s+helmet+comes+off%2C+he%27s+down&rft.pub=Profootballtalk.com&rft.date=2013-11-16&rft.aulast=Smith&rft.aufirst=Michael+David&rft_id=http%3A%2F%2Fprofootballtalk.nbcsports.com%2F2013%2F11%2F16%2Fwhen-a-runners-helmet-comes-off-hes-down%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-The_Orchestration_of_the_Chain_Gang-92"><span class="mw-cite-backlink">^ <a href="#cite_ref-The_Orchestration_of_the_Chain_Gang_92-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-The_Orchestration_of_the_Chain_Gang_92-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite class="citation news">Branch, John (December 31, 2008). <a rel="nofollow" class="external text" href="https://www.nytimes.com/2009/01/01/sports/football/01chainside.html">"The Orchestration of the Chain Gang"</a>. <i><a href="/wiki/The_New_York_Times" title="The New York Times">The New York Times</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20121229055115/http://www.nytimes.com/2009/01/01/sports/football/01chainside.html">Archived</a> from the original on December 29, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">December 19,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+New+York+Times&rft.atitle=The+Orchestration+of+the+Chain+Gang&rft.date=2008-12-31&rft.aulast=Branch&rft.aufirst=John&rft_id=https%3A%2F%2Fwww.nytimes.com%2F2009%2F01%2F01%2Fsports%2Ffootball%2F01chainside.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Yellow_line-93"><span class="mw-cite-backlink"><b><a href="#cite_ref-Yellow_line_93-0">^</a></b></span> <span class="reference-text"><cite class="citation web">St. John, Allan (December 18, 2009). <a rel="nofollow" class="external text" href="http://www.popularmechanics.com/outdoors/sports/4301993">"The Tech Behind the Football's Broadcast-Only First Down Line"</a>. <a href="/wiki/Popular_Mechanics" title="Popular Mechanics">Popular Mechanics</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20121213000449/http://www.popularmechanics.com/outdoors/sports/4301993">Archived</a> from the original on December 13, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">November 2,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+Tech+Behind+the+Football%27s+Broadcast-Only+First+Down+Line&rft.pub=Popular+Mechanics&rft.date=2009-12-18&rft.aulast=St.+John&rft.aufirst=Allan&rft_id=http%3A%2F%2Fwww.popularmechanics.com%2Foutdoors%2Fsports%2F4301993&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-PFRA-94"><span class="mw-cite-backlink">^ <a href="#cite_ref-PFRA_94-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-PFRA_94-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-PFRA_94-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><cite class="citation journal">Hogrogian, John (1999). <a rel="nofollow" class="external text" href="http://profootballresearchers.com/archives/Website_Files/Coffin_Corner/21-06-832.pdf">"The Last Drop Kick?"</a> <span class="cs1-format">(PDF)</span>. <i><a href="/wiki/The_Coffin_Corner" class="mw-redirect" title="The Coffin Corner">The Coffin Corner</a></i>. <b>21</b> (6). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150618235835/http://profootballresearchers.com/archives/Website_Files/Coffin_Corner/21-06-832.pdf">Archived</a> <span class="cs1-format">(PDF)</span> from the original on June 18, 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">October 22,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Coffin+Corner&rft.atitle=The+Last+Drop+Kick%3F&rft.volume=21&rft.issue=6&rft.date=1999&rft.aulast=Hogrogian&rft.aufirst=John&rft_id=http%3A%2F%2Fprofootballresearchers.com%2Farchives%2FWebsite_Files%2FCoffin_Corner%2F21-06-832.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-The_last_dropkick-95"><span class="mw-cite-backlink">^ <a href="#cite_ref-The_last_dropkick_95-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-The_last_dropkick_95-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.profootballhof.com/hof/release.aspx?release_id=1481">"The last dropkick"</a>. <a href="/wiki/Pro_Football_Hall_of_Fame" title="Pro Football Hall of Fame">Pro Football Hall of Fame</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20121021234605/http://www.profootballhof.com/hof/release.aspx?release_id=1481">Archived</a> from the original on October 21, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">October 8,</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+last+dropkick&rft.pub=Pro+Football+Hall+of+Fame&rft_id=http%3A%2F%2Fwww.profootballhof.com%2Fhof%2Frelease.aspx%3Frelease_id%3D1481&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-NFL_Rules_2012,_p._50-96"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_Rules_2012,_p._50_96-0">^</a></b></span> <span class="reference-text">NFL Rules 2012, p. 50.</span>
</li>
<li id="cite_note-NCAA_Rules_2011–2012,_p._34-97"><span class="mw-cite-backlink">^ <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._34_97-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._34_97-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">NCAA Rules 2011–2012, p. 34.</span>
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<li id="cite_note-NFHS_Rules_2012,_p._32-98"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_p._32_98-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, p. 32.</span>
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<li id="cite_note-NFL_Rules_2012,_p._6-99"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_Rules_2012,_p._6_99-0">^</a></b></span> <span class="reference-text">NFL Rules 2012, p. 6.</span>
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<li id="cite_note-NCAA_Rules_2011–2012,_p._30-100"><span class="mw-cite-backlink"><b><a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_p._30_100-0">^</a></b></span> <span class="reference-text">NCAA Rules 2011–2012, p. 30.</span>
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<li id="cite_note-NFHS_Rules_2012,_p._27-101"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_p._27_101-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, p. 27.</span>
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<li id="cite_note-NFL_Rules_2012,_pp._8-9-102"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_Rules_2012,_pp._8-9_102-0">^</a></b></span> <span class="reference-text">NFL Rules 2012, pp. 8–9.</span>
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<li id="cite_note-NFHS_Rules_2012,_pp._31-32-103"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_pp._31-32_103-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, pp. 31–32.</span>
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<li id="cite_note-NFL_Rules_2012,_pp._29-30-104"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_Rules_2012,_pp._29-30_104-0">^</a></b></span> <span class="reference-text">NFL Rules 2012, pp. 29–30.</span>
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<li id="cite_note-NCAA_Rules_2011–2012,_pp._61-64-105"><span class="mw-cite-backlink"><b><a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_pp._61-64_105-0">^</a></b></span> <span class="reference-text">NCAA Rules 2011–2012, pp. 61–64.</span>
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<li id="cite_note-NFHS_Rules_2012,_pp._15,_46,_52–53-106"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_pp._15,_46,_52%E2%80%9353_106-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, pp. 15, 46, 52–53.</span>
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<li id="cite_note-NFL_Rules_2012,_pp._33-34,_50–53-107"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_Rules_2012,_pp._33-34,_50%E2%80%9353_107-0">^</a></b></span> <span class="reference-text">NFL Rules 2012, pp. 33–34, 50–53.</span>
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<li id="cite_note-NCAA_Rules_2011–2012,_pp._55-56,_63–64-108"><span class="mw-cite-backlink"><b><a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_pp._55-56,_63%E2%80%9364_108-0">^</a></b></span> <span class="reference-text">NCAA Rules 2011–2012, pp. 55–56, 63–64.</span>
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<li id="cite_note-NFHS_Rules_2012,_pp._49,_53–54-109"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_pp._49,_53%E2%80%9354_109-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, pp. 49,  53–54.</span>
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<li id="cite_note-NFL_Rules_2012,_p._7-110"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_Rules_2012,_p._7_110-0">^</a></b></span> <span class="reference-text">NFL Rules 2012, pp. 7, 54–55.</span>
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<li id="cite_note-NCAA_Rules_2011–2012,_pp._30,_66–67-111"><span class="mw-cite-backlink"><b><a href="#cite_ref-NCAA_Rules_2011%E2%80%932012,_pp._30,_66%E2%80%9367_111-0">^</a></b></span> <span class="reference-text">NCAA Rules 2011–2012, pp. 30, 66–67.</span>
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<li id="cite_note-NFHS_Rules_2012,_p._2756,-112"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFHS_Rules_2012,_p._2756,_112-0">^</a></b></span> <span class="reference-text">NFHS Rules 2012, pp. 27, 56.</span>
</li>
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<li id="cite_note-No_New_Year's_Day_Bowl_Games?_Bah,_Humbug-160"><span class="mw-cite-backlink"><b><a href="#cite_ref-No_New_Year's_Day_Bowl_Games?_Bah,_Humbug_160-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Wischnowsky, Dave (December 30, 2011). <a rel="nofollow" class="external text" href="http://chicago.cbslocal.com/2011/12/30/wisch-no-new-years-day-bowl-games-bah-humbug/">"No New Year's Day Bowl Games? Bah, Humbug"</a>. <a href="/wiki/CBS_Chicago" class="mw-redirect" title="CBS Chicago">CBS Chicago</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140429050123/http://chicago.cbslocal.com/2011/12/30/wisch-no-new-years-day-bowl-games-bah-humbug/">Archived</a> from the original on April 29, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">April 28,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=No+New+Year%27s+Day+Bowl+Games%3F+Bah%2C+Humbug&rft.pub=CBS+Chicago&rft.date=2011-12-30&rft.aulast=Wischnowsky&rft.aufirst=Dave&rft_id=http%3A%2F%2Fchicago.cbslocal.com%2F2011%2F12%2F30%2Fwisch-no-new-years-day-bowl-games-bah-humbug%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-164"><span class="mw-cite-backlink"><b><a href="#cite_ref-164">^</a></b></span> <span class="reference-text">Smith (2009), p. 146.</span>
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<li id="cite_note-165"><span class="mw-cite-backlink"><b><a href="#cite_ref-165">^</a></b></span> <span class="reference-text"><cite class="citation news"><a rel="nofollow" class="external text" href="https://www.theodysseyonline.com/why-american-football-is-stupid">"Why American Football Is Stupid"</a>. <i><a href="/wiki/Odyssey_(publication)" title="Odyssey (publication)">Odyssey</a></i>. November 24, 2015. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170807021004/https://www.theodysseyonline.com/why-american-football-is-stupid">Archived</a> from the original on August 7, 2017<span class="reference-accessdate">. Retrieved <span class="nowrap">July 20,</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Odyssey&rft.atitle=Why+American+Football+Is+Stupid&rft.date=2015-11-24&rft_id=https%3A%2F%2Fwww.theodysseyonline.com%2Fwhy-american-football-is-stupid&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Friday_night_lights:_American_football_in_Japan_a_high_school_hit-171"><span class="mw-cite-backlink"><b><a href="#cite_ref-Friday_night_lights:_American_football_in_Japan_a_high_school_hit_171-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Jardine, Lisa (September 28, 2010). <a rel="nofollow" class="external text" href="http://travel.cnn.com/tokyo/play/friday-night-lights-japanese-american-football-player-dream-686573">"Friday night lights: American football in Japan a high school hit"</a>. <a href="/wiki/CNN_Travel" class="mw-redirect" title="CNN Travel">CNN Travel</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140417200538/http://travel.cnn.com/tokyo/play/friday-night-lights-japanese-american-football-player-dream-686573">Archived</a> from the original on April 17, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">April 23,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Friday+night+lights%3A+American+football+in+Japan+a+high+school+hit&rft.pub=CNN+Travel&rft.date=2010-09-28&rft.aulast=Jardine&rft.aufirst=Lisa&rft_id=http%3A%2F%2Ftravel.cnn.com%2Ftokyo%2Fplay%2Ffriday-night-lights-japanese-american-football-player-dream-686573&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Obic_captures_third_straight_Rice_Bowl-172"><span class="mw-cite-backlink"><b><a href="#cite_ref-Obic_captures_third_straight_Rice_Bowl_172-0">^</a></b></span> <span class="reference-text"><cite class="citation news"><a rel="nofollow" class="external text" href="http://www.japantimes.co.jp/sports/2013/01/04/more-sports/obic-captures-third-straight-rice-bowl/">"Obic captures third straight Rice Bowl"</a>. <i><a href="/wiki/The_Japan_Times" title="The Japan Times">The Japan Times</a></i>. January 3, 2013. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140427000923/http://www.japantimes.co.jp/sports/2013/01/04/more-sports/obic-captures-third-straight-rice-bowl/">Archived</a> from the original on April 27, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">April 23,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Japan+Times&rft.atitle=Obic+captures+third+straight+Rice+Bowl&rft.date=2013-01-03&rft_id=http%3A%2F%2Fwww.japantimes.co.jp%2Fsports%2F2013%2F01%2F04%2Fmore-sports%2Fobic-captures-third-straight-rice-bowl%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Touchdown_in_the_U.K.:_Britain's_Long-Distance_Affair_with_the_NFL-173"><span class="mw-cite-backlink"><b><a href="#cite_ref-Touchdown_in_the_U.K.:_Britain's_Long-Distance_Affair_with_the_NFL_173-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Langford, John (February 17, 2014). <a rel="nofollow" class="external text" href="http://www.bbcamerica.com/anglophenia/2014/02/touchdown-u-k-british-nfl-fans-cope-long-distance-love-affair/">"Touchdown in the U.K.: Britain's Long-Distance Affair with the NFL"</a>. <a href="/wiki/BBC_America" title="BBC America">BBC America</a>. Anglophenia. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20141110003109/http://www.bbcamerica.com/anglophenia/2014/02/touchdown-u-k-british-nfl-fans-cope-long-distance-love-affair/">Archived</a> from the original on November 10, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">April 17,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Touchdown+in+the+U.K.%3A+Britain%27s+Long-Distance+Affair+with+the+NFL&rft.pub=BBC+America.+Anglophenia&rft.date=2014-02-17&rft.aulast=Langford&rft.aufirst=John&rft_id=http%3A%2F%2Fwww.bbcamerica.com%2Fanglophenia%2F2014%2F02%2Ftouchdown-u-k-british-nfl-fans-cope-long-distance-love-affair%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-Super_Bowl_caps_UK's_growing_gridiron_fever-174"><span class="mw-cite-backlink"><b><a href="#cite_ref-Super_Bowl_caps_UK's_growing_gridiron_fever_174-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Morrison, Sarah; Hayman-Brown, Isabel (February 5, 2012). <a rel="nofollow" class="external text" href="https://www.independent.co.uk/sport/general/others/super-bowl-caps-uks-growing-gridiron-fever-6423166.html">"Super Bowl caps UK's growing gridiron fever"</a>. <i><a href="/wiki/The_Independent" title="The Independent">The Independent</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150705211444/http://www.independent.co.uk/sport/general/others/super-bowl-caps-uks-growing-gridiron-fever-6423166.html">Archived</a> from the original on July 5, 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">June 19,</span> 2015</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+Independent&rft.atitle=Super+Bowl+caps+UK%27s+growing+gridiron+fever&rft.date=2012-02-05&rft.aulast=Morrison&rft.aufirst=Sarah&rft.au=Hayman-Brown%2C+Isabel&rft_id=https%3A%2F%2Fwww.independent.co.uk%2Fsport%2Fgeneral%2Fothers%2Fsuper-bowl-caps-uks-growing-gridiron-fever-6423166.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-The_Game_Is_American,_but_the_View,_Alpine-175"><span class="mw-cite-backlink"><b><a href="#cite_ref-The_Game_Is_American,_but_the_View,_Alpine_175-0">^</a></b></span> <span class="reference-text"><cite class="citation news">Tagliabue, John (April 14, 2011). <a rel="nofollow" class="external text" href="https://www.nytimes.com/2011/04/15/world/europe/15swiss.html">"The Game Is American, but the View, Alpine"</a>. <i><a href="/wiki/The_New_York_Times" title="The New York Times">The New York Times</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150607082047/http://www.nytimes.com/2011/04/15/world/europe/15swiss.html">Archived</a> from the original on June 7, 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">April 17,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+New+York+Times&rft.atitle=The+Game+Is+American%2C+but+the+View%2C+Alpine&rft.date=2011-04-14&rft.aulast=Tagliabue&rft.aufirst=John&rft_id=https%3A%2F%2Fwww.nytimes.com%2F2011%2F04%2F15%2Fworld%2Feurope%2F15swiss.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-184"><span class="mw-cite-backlink"><b><a href="#cite_ref-184">^</a></b></span> <span class="reference-text"><cite class="citation web">Fitz-Gerald, Sean (June 4, 2008). <a rel="nofollow" class="external text" href="http://www.nationalpost.com/ends+working+agreement+with/563856/story.html">"CFL ends working agreement with NFL"</a>. <i><a href="/wiki/National_Post" title="National Post">National Post</a></i><span class="reference-accessdate">. Retrieved <span class="nowrap">August 10,</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=National+Post&rft.atitle=CFL+ends+working+agreement+with+NFL&rft.date=2008-06-04&rft.aulast=Fitz-Gerald&rft.aufirst=Sean&rft_id=http%3A%2F%2Fwww.nationalpost.com%2Fends%2Bworking%2Bagreement%2Bwith%2F563856%2Fstory.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
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<li id="cite_note-185"><span class="mw-cite-backlink"><b><a href="#cite_ref-185">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="https://www.cfl.ca/2019/01/31/cfl-gfl-form-strategic-football-partnership/">"CFL and GFL form strategic football partnership"</a>. <a href="/wiki/Canadian_Football_League" title="Canadian Football League">Canadian Football League</a>. January 31, 2019<span class="reference-accessdate">. Retrieved <span class="nowrap">August 10,</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=CFL+and+GFL+form+strategic+football+partnership&rft.pub=Canadian+Football+League&rft.date=2019-01-31&rft_id=https%3A%2F%2Fwww.cfl.ca%2F2019%2F01%2F31%2Fcfl-gfl-form-strategic-football-partnership%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
</li>
<li id="cite_note-Staying_in_the_Game_on_Football's_Fringe-186"><span class="mw-cite-backlink"><b><a href="#cite_ref-Staying_in_the_Game_on_Football's_Fringe_186-0">^</a></b></span> <span class="reference-text"><cite class="citation news">Tainer, Mike (June 27, 2011). <a rel="nofollow" class="external text" href="https://www.nytimes.com/2011/06/28/sports/football/staying-in-the-game-on-footballs-fringe.html">"Staying in the Game on Football's Fringe"</a>. <i><a href="/wiki/The_New_York_Times" title="The New York Times">The New York Times</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20120821234055/http://www.nytimes.com/2011/06/28/sports/football/staying-in-the-game-on-footballs-fringe.html">Archived</a> from the original on August 21, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">January 19,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+New+York+Times&rft.atitle=Staying+in+the+Game+on+Football%27s+Fringe&rft.date=2011-06-27&rft.aulast=Tainer&rft.aufirst=Mike&rft_id=https%3A%2F%2Fwww.nytimes.com%2F2011%2F06%2F28%2Fsports%2Ffootball%2Fstaying-in-the-game-on-footballs-fringe.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
</li>
<li id="cite_note-GleesonChap7-187"><span class="mw-cite-backlink"><b><a href="#cite_ref-GleesonChap7_187-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFGleeson2019" class="citation">Gleeson, Scott (November 27, 2019), <a rel="nofollow" class="external text" href="https://www.usatoday.com/story/sports/nfl/2019/11/27/arena-football-league-declares-bankruptcy-shuts-down/4322126002/">"Arena Football League files for bankruptcy, ceases all operations"</a>, <i><a href="/wiki/USA_Today" title="USA Today">USA Today</a></i><span class="reference-accessdate">, retrieved <span class="nowrap">November 27,</span> 2019</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=USA+Today&rft.atitle=Arena+Football+League+files+for+bankruptcy%2C+ceases+all+operations&rft.date=2019-11-27&rft.aulast=Gleeson&rft.aufirst=Scott&rft_id=https%3A%2F%2Fwww.usatoday.com%2Fstory%2Fsports%2Fnfl%2F2019%2F11%2F27%2Farena-football-league-declares-bankruptcy-shuts-down%2F4322126002%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
</li>
<li id="cite_note-Arena_football:_Is_it_America's_fifth_major_sport?-188"><span class="mw-cite-backlink"><b><a href="#cite_ref-Arena_football:_Is_it_America's_fifth_major_sport?_188-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Colston, Chris (April 15, 2007). <a rel="nofollow" class="external text" href="http://usatoday30.usatoday.com/sports/football/2007-04-13-sw-arena-football_N.htm">"Arena football: Is it America's fifth major sport?"</a>. <i><a href="/wiki/USA_Today" title="USA Today">USA Today</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20131019122357/http://usatoday30.usatoday.com/sports/football/2007-04-13-sw-arena-football_N.htm">Archived</a> from the original on October 19, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">January 10,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=USA+Today&rft.atitle=Arena+football%3A+Is+it+America%27s+fifth+major+sport%3F&rft.date=2007-04-15&rft.aulast=Colston&rft.aufirst=Chris&rft_id=http%3A%2F%2Fusatoday30.usatoday.com%2Fsports%2Ffootball%2F2007-04-13-sw-arena-football_N.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
</li>
<li id="cite_note-NFL_FLAG_football_is_about_fun_and_fundamentals-189"><span class="mw-cite-backlink"><b><a href="#cite_ref-NFL_FLAG_football_is_about_fun_and_fundamentals_189-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Mills, Amy (July 30, 2013). <a rel="nofollow" class="external text" href="http://usafootball.com/blog/fundamentals-and-performance/nfl-flag-football-about-fun-and-fundamentals">"NFL FLAG football is about fun and fundamentals"</a>. <a href="/wiki/USA_Football" title="USA Football">USA Football</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140420053206/http://usafootball.com/blog/fundamentals-and-performance/nfl-flag-football-about-fun-and-fundamentals">Archived</a> from the original on April 20, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">April 19,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=NFL+FLAG+football+is+about+fun+and+fundamentals&rft.pub=USA+Football&rft.date=2013-07-30&rft.aulast=Mills&rft.aufirst=Amy&rft_id=http%3A%2F%2Fusafootball.com%2Fblog%2Ffundamentals-and-performance%2Fnfl-flag-football-about-fun-and-fundamentals&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
</li>
<li id="cite_note-Proper_flag_pull_takes_fast_feet_and_discipline-190"><span class="mw-cite-backlink"><b><a href="#cite_ref-Proper_flag_pull_takes_fast_feet_and_discipline_190-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Musto, Adam (March 19, 2012). <a rel="nofollow" class="external text" href="http://usafootball.com/news/coaches/proper-flag-pull-takes-fast-feet-and-discipline">"Proper flag pull takes fast feet and discipline"</a>. <a href="/wiki/USA_Football" title="USA Football">USA Football</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140420052244/http://usafootball.com/news/coaches/proper-flag-pull-takes-fast-feet-and-discipline">Archived</a> from the original on April 20, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">April 19,</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Proper+flag+pull+takes+fast+feet+and+discipline&rft.pub=USA+Football&rft.date=2012-03-19&rft.aulast=Musto&rft.aufirst=Adam&rft_id=http%3A%2F%2Fusafootball.com%2Fnews%2Fcoaches%2Fproper-flag-pull-takes-fast-feet-and-discipline&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
</li>
<li id="cite_note-The_32_Rules_of_Thanksgiving_Touch_Football-191"><span class="mw-cite-backlink"><b><a href="#cite_ref-The_32_Rules_of_Thanksgiving_Touch_Football_191-0">^</a></b></span> <span class="reference-text"><cite class="citation web">Gay, Jason. <a rel="nofollow" class="external text" href="https://www.wsj.com/articles/SB10001424052970204531404577050370294096452">"The 32 Rules of Thanksgiving Touch Football"</a>. <i><a href="/wiki/The_Wall_Street_Journal" title="The Wall Street Journal">The Wall Street Journal</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150101014214/http://www.wsj.com/articles/SB10001424052970204531404577050370294096452">Archived</a> from the original on January 1, 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">January 10,</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+Wall+Street+Journal&rft.atitle=The+32+Rules+of+Thanksgiving+Touch+Football&rft.aulast=Gay&rft.aufirst=Jason&rft_id=https%3A%2F%2Fwww.wsj.com%2Farticles%2FSB10001424052970204531404577050370294096452&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></span>
</li>
</ol></div></div>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(12)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="References">References</span></h2><section class="mf-section-12 collapsible-block" id="mf-section-12">
<style data-mw-deduplicate="TemplateStyles:r886047268">.mw-parser-output .refbegin{font-size:90%;margin-bottom:0.5em}.mw-parser-output .refbegin-hanging-indents>ul{list-style-type:none;margin-left:0}.mw-parser-output .refbegin-hanging-indents>ul>li,.mw-parser-output .refbegin-hanging-indents>dl>dd{margin-left:0;padding-left:3.2em;text-indent:-3.2em;list-style:none}.mw-parser-output .refbegin-100{font-size:100%}</style><div class="refbegin reflist" style="">
<ul><li><cite class="citation book">Bennett, Tom (1976). <i>The Pro Style: The Complete Guide to Understanding National Football League Strategy</i>. Los Angeles: National Football League Properties, Inc., Creative Services Division.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Pro+Style%3A+The+Complete+Guide+to+Understanding+National+Football+League+Strategy&rft.place=Los+Angeles&rft.pub=National+Football+League+Properties%2C+Inc.%2C+Creative+Services+Division&rft.date=1976&rft.aulast=Bennett&rft.aufirst=Tom&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></li>
<li><cite class="citation web">Colgate, Bob, ed. (2011). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160304084406/http://refereenation.docs.s3.amazonaws.com/2011_NFHS_Football_Rules.pdf">"2011 NFHS Football Rules Book"</a> <span class="cs1-format">(PDF)</span>. Gardener, Robert B.. <a href="/wiki/National_Federation_of_State_High_School_Associations" title="National Federation of State High School Associations">NFHS Publications</a>. Archived from <a rel="nofollow" class="external text" href="http://refereenation.docs.s3.amazonaws.com/2011_NFHS_Football_Rules.pdf">the original</a> <span class="cs1-format">(PDF)</span> on March 4, 2016.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=2011+NFHS+Football+Rules+Book&rft.pub=Gardener%2C+Robert+B..+NFHS+Publications&rft.date=2011&rft_id=http%3A%2F%2Frefereenation.docs.s3.amazonaws.com%2F2011_NFHS_Football_Rules.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></li>
<li><cite class="citation book">Jozsa, Frank P. (2004). <i>Sports Capitalism: The Foreign Business of American Professional Leagues</i>. <a href="/wiki/Ashgate_Publishing" title="Ashgate Publishing">Ashgate Publishing</a>. <a href="/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/wiki/Special:BookSources/978-0-7546-4185-8" title="Special:BookSources/978-0-7546-4185-8"><bdi>978-0-7546-4185-8</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Sports+Capitalism%3A+The+Foreign+Business+of+American+Professional+Leagues&rft.pub=Ashgate+Publishing&rft.date=2004&rft.isbn=978-0-7546-4185-8&rft.aulast=Jozsa&rft.aufirst=Frank+P.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></li>
<li><cite class="citation book"><a href="/wiki/David_M._Nelson" title="David M. Nelson">Nelson, David M.</a> (December 12, 1993). <a rel="nofollow" class="external text" href="https://books.google.com/?id=OmwfnipKuogC&printsec=frontcover#v=onepage"><i>The Anatomy of a Game: Football, the Rules, and the Men Who Made the Game</i></a> (1 ed.). <a href="/wiki/University_of_Delaware_Press" title="University of Delaware Press">University of Delaware Press</a>. p. 15. <a href="/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/wiki/Special:BookSources/978-0-87413-455-1" title="Special:BookSources/978-0-87413-455-1"><bdi>978-0-87413-455-1</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Anatomy+of+a+Game%3A+Football%2C+the+Rules%2C+and+the+Men+Who+Made+the+Game&rft.pages=15&rft.edition=1&rft.pub=University+of+Delaware+Press&rft.date=1993-12-12&rft.isbn=978-0-87413-455-1&rft.aulast=Nelson&rft.aufirst=David+M.&rft_id=https%3A%2F%2Fbooks.google.com%2F%3Fid%3DOmwfnipKuogC%26printsec%3Dfrontcover%23v%3Donepage&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></li>
<li><cite class="citation web"><a rel="nofollow" class="external text" href="http://static.nfl.com/static/content/public/image/rulebook/pdfs/2012%20-%20Rule%20Book.pdf">"Official Playing Rules and Casebook of the National Football League"</a> <span class="cs1-format">(PDF)</span>. <a href="/wiki/National_Football_League" title="National Football League">National Football League</a>. 2012.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Official+Playing+Rules+and+Casebook+of+the+National+Football+League&rft.pub=National+Football+League&rft.date=2012&rft_id=http%3A%2F%2Fstatic.nfl.com%2Fstatic%2Fcontent%2Fpublic%2Fimage%2Frulebook%2Fpdfs%2F2012%2520-%2520Rule%2520Book.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></li>
<li><cite class="citation web">Redding, Rogers (2011–2012).  Halpin, Ty (ed.). <a rel="nofollow" class="external text" href="http://www.ncaapublications.com/productdownloads/FR12.pdf">"NCAA Football Rules and Interpretations"</a> <span class="cs1-format">(PDF)</span>. <a href="/wiki/National_Collegiate_Athletic_Association" title="National Collegiate Athletic Association">National Collegiate Athletic Association</a>. <a href="/wiki/International_Standard_Serial_Number" title="International Standard Serial Number">ISSN</a> <a rel="nofollow" class="external text" href="//www.worldcat.org/issn/0736-5144">0736-5144</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=NCAA+Football+Rules+and+Interpretations&rft.pub=National+Collegiate+Athletic+Association&rft.date=2011%2F2012&rft.issn=0736-5144&rft.aulast=Redding&rft.aufirst=Rogers&rft_id=http%3A%2F%2Fwww.ncaapublications.com%2Fproductdownloads%2FFR12.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></li>
<li><cite class="citation book">Smith, Earl, ed. (August 11, 2009). <a rel="nofollow" class="external text" href="https://books.google.com/?id=Vhbpot6Jk1EC&pg=PA146&dq=masculinity+football#v=onepage&q=masculinity%20football"><i>Sociology of Sport and Social Theory</i></a>. Human Kinetics. <a href="/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/wiki/Special:BookSources/978-0-7360-7572-5" title="Special:BookSources/978-0-7360-7572-5"><bdi>978-0-7360-7572-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Sociology+of+Sport+and+Social+Theory&rft.pub=Human+Kinetics&rft.date=2009-08-11&rft.isbn=978-0-7360-7572-5&rft_id=https%3A%2F%2Fbooks.google.com%2F%3Fid%3DVhbpot6Jk1EC%26pg%3DPA146%26dq%3Dmasculinity%2Bfootball%23v%3Donepage%26q%3Dmasculinity%2520football&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></li>
<li><cite class="citation book">Vancil, Mark (<i>Ed.</i>) (2000). <i>ABC Sports College Football All-Time All-America Team</i>. New York: <a href="/wiki/Hachette_Books" title="Hachette Books">Hyperion Books</a>. <a href="/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/wiki/Special:BookSources/978-0-7868-6710-3" title="Special:BookSources/978-0-7868-6710-3"><bdi>978-0-7868-6710-3</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=ABC+Sports+College+Football+All-Time+All-America+Team&rft.place=New+York&rft.pub=Hyperion+Books&rft.date=2000&rft.isbn=978-0-7868-6710-3&rft.aulast=Vancil&rft.aufirst=Mark+%28%27%27Ed.%27%27%29&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAmerican+football" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r935243608"></li></ul></div>
</section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(13)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="Further_reading">Further reading</span></h2><section class="mf-section-13 collapsible-block" id="mf-section-13">
<ul><li><i><a rel="nofollow" class="external text" href="https://www.worldcat.org/title/football-great-writing-about-the-national-sport/oclc/895301624/editions">Football: Great Writing About the National Sport</a></i>, edited by John Schulian; 2014 (New York: <a href="/wiki/Library_of_America" title="Library of America">Library of America</a>)</li></ul></section><h2 class="section-heading" onclick="javascript:mfTempOpenSection(14)"><div class="mw-ui-icon mw-ui-icon-element indicator mw-ui-icon-small mw-ui-icon-flush-left"></div><span class="mw-headline" id="External_links">External links</span></h2><section class="mf-section-14 collapsible-block" id="mf-section-14">
<div id="section_SpokenWikipedia" class="infobox sisterproject plainlinks haudio"><div style="text-align: center; white-space:nowrap"><b>Listen to this article</b> (<a href="/wiki/File:En-American_Football-article.ogg" title="File:En-American Football-article.ogg">info/dl</a>)
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<div style="font-size: xx-small; line-height: 1.6em; margin-left: 60px;">This audio file was created from a revision of the article "<span class="fn">American football</span>" dated July 5, 2014, and does not reflect subsequent edits to the article. (<a href="/wiki/Wikipedia:Media_help" class="mw-redirect" title="Wikipedia:Media help">Audio help</a>)</div>
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<div role="navigation" aria-labelledby="sister-projects" class="metadata plainlinks sistersitebox plainlist mbox-small" style="border:1px solid #aaa; padding:0; background:#f9f9f9;"><div style="padding: 0.75em 0; text-align: center;"><b style="display:block;">American football</b>at Wikipedia's <a href="/wiki/Wikipedia:Wikimedia_sister_projects" title="Wikipedia:Wikimedia sister projects"><span id="sister-projects">sister projects</span></a></div><ul style="border-top:1px solid #aaa; padding: 0.75em 0; width:217px; margin:0 auto;"><li style="min-height: 31px;"><span style="display: inline-block; width: 31px; line-height: 31px; vertical-align: middle; text-align: center;"><noscript><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/0/06/Wiktionary-logo-v2.svg/27px-Wiktionary-logo-v2.svg.png" decoding="async" width="27" height="27" style="vertical-align: middle" data-file-width="391" data-file-height="391"></noscript><span class="lazy-image-placeholder" style="width: 27px;height: 27px;" data-src="//upload.wikimedia.org/wikipedia/en/thumb/0/06/Wiktionary-logo-v2.svg/27px-Wiktionary-logo-v2.svg.png" data-alt="" data-width="27" data-height="27" data-srcset="//upload.wikimedia.org/wikipedia/en/thumb/0/06/Wiktionary-logo-v2.svg/41px-Wiktionary-logo-v2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/0/06/Wiktionary-logo-v2.svg/54px-Wiktionary-logo-v2.svg.png 2x"> </span></span><span style="display: inline-block; margin-left: 4px; width: 182px; vertical-align: middle;"><a href="https://en.wiktionary.org/wiki/American_football" class="extiw" title="wikt:American football">Definitions</a> from Wiktionary</span>
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<ul><li><a rel="nofollow" class="external text" href="https://curlie.org/Sports/Football/American/">American football</a> at <a href="/wiki/Curlie" class="mw-redirect" title="Curlie">Curlie</a></li>
<li><a rel="nofollow" class="external text" href="http://nfl.com/">National Football League</a></li>
<li><a rel="nofollow" class="external text" href="http://ifaf.info/">International Federation of American Football</a></li>
<li><a rel="nofollow" class="external text" href="http://nfl-360.com/">NFL 360, an introductory website to football rules</a></li>
<li><a rel="nofollow" class="external text" href="https://www.loc.gov/item/mp73006300/">Excerpts of a 1903 football game between the University of Chicago and University of Michigan</a></li></ul>








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