Founding and history
On August 20, 1920, a meeting was held by representatives of the
Rock Island Independents and
Dayton Triangles at the Jordan and
Hupmobile auto showroom in
Canton, Ohio. This meeting resulted in the formation of the American Professional Football Conference (APFC), a group who, according to the Canton Evening Repository, intended to "raise the standard of professional football in every way possible, to eliminate bidding for players between rival clubs and to secure cooperation in the formation of schedules".
 Another meeting held on September 17, 1920 resulted in the renaming of the league to the American Professional Football Association (APFA).
 The league hired
Jim Thorpe as its first president, and consisted of 14 teams. Only two of these teams, the
Decatur Staleys (now the Chicago Bears) and the
Chicago Cardinals (now the Arizona Cardinals), remain.
won the first APFA (NFL) Championship.
Although the league did not maintain official standings for its
1920 inaugural season and teams played schedules that included non-league opponents, the APFA awarded the Akron Pros the championship by virtue of their 8–0–3 (8 wins, 0 losses, and 3
 The first event occurred on September 26, 1920 when the
Rock Island Independents defeated the non-league St. Paul Ideals 48–0 at
 On October 3, 1920, the first full week of league play occurred.
 The following season resulted in the Chicago Staleys
controversially winning the title over the
 On June 24, 1922, the APFA changed its name to the National Football League (NFL).
1932, the season ended with the Chicago Bears (6–1–6) and the
Portsmouth Spartans (6–1–4) tied for first in the league standings.
 At the time, teams were ranked on a single table and the team with the highest
winning percentage (not including ties, which were not counted towards the standings) at the end of the season was declared the champion; the only tiebreaker was that in the event of a tie, if two teams played twice in a season, the result of the second game determined the title (the source of the 1921 controversy). This method had been used since the league's creation in 1920, but no situation had been encountered where two teams were tied for first. The league quickly determined that a
playoff game between Chicago and Portsmouth was needed to decide the league's champion. The teams were originally scheduled to play the playoff game, officially a regular season game that would count towards the regular season standings, at
Wrigley Field in Chicago, but a combination of heavy snow and extreme cold forced the game to be moved indoors to
Chicago Stadium, which did not have a regulation-size football field. Playing with altered rules to accommodate the smaller playing field, the Bears won the game 9–0 and thus won the championship. Fan interest in the de facto championship game led the NFL, beginning in
1933, to split into
two divisions with a championship game to be played between the division champions.
1934 season also marked the first of 12 seasons in which African Americans were
. The de facto ban was rescinded in
1946, following public pressure and coinciding with the removal of
a similar ban in
Major League Baseball.
The NFL was always the foremost professional football league in the United States; it nevertheless faced a large number of rival professional leagues through the 1930s and 1940s. Rival leagues included at least three separate
(AAFC), on top of various regional leagues of varying caliber. Three NFL teams trace their histories to these rival leagues, including the
Los Angeles Rams (who came from a 1936 iteration of the American Football League), the
Cleveland Browns and
San Francisco 49ers (the last two of which came from the AAFC). By the 1950s, the NFL had an effective monopoly on professional football in the United States; its only competition in North America was the professional
circuit, which formally became the
(CFL) in 1958. With Canadian football being
a different football code than the American game, the CFL established a niche market in Canada and still survives as an independent league.
A new professional league, the fourth
(AFL), began play in 1960. The upstart AFL began to challenge the established NFL in popularity, gaining lucrative television contracts and engaging in a bidding war with the NFL for free agents and draft picks. The two leagues announced a
merger on June 8, 1966, to take full effect in 1970. In the meantime, the leagues would hold a common draft and championship game. The game, the
Super Bowl, was held four times before the merger, with the NFL winning
Super Bowl I and
Super Bowl II, and the AFL winning
Super Bowl III and
Super Bowl IV.
 After the league merged, it was reorganized into two conferences: the
(NFC), consisting of most of the pre-merger NFL teams, and the
(AFC), consisting of all of the AFL teams as well as three pre-merger NFL teams.
Today, the NFL is consideredPete Rozelle, who led the league from 1960 to 1989. Overall annual attendance increased from three million at the beginning of his tenure to seventeen million by the end of his tenure, and 400 million viewers watched 1989's
Super Bowl XXIII. The NFL established
in 1963. The league's licensing wing, NFL Properties earns the league billions of dollars annually; Rozelle's tenure also marked the creation of
NFL Charities and a national partnership with
Paul Tagliabue was elected as commissioner to succeed Rozelle; his seventeen-year tenure, which ended in 2006, was marked by large increases in television contracts and the addition of four expansion teams,
 as well as the introduction of league initiatives to increase the number of minorities in league and team management roles.
 The league's current Commissioner,
Roger Goodell, has focused on reducing the number of illegal hits and making the sport safer, mainly through fining or suspending players who break rules.
 These actions are among many the NFL is taking to reduce
concussions and improve player safety.
the most popular sports league in North America; much of its growth is attributed to former Commissioner
Season and playoff development
From 1920 to 1934, the NFL did not have a set number of games for teams to play, instead setting a minimum. The league mandated a 12-game regular season for each team beginning in
1935, later shortening this to 11 games in
1937 and 10 games in
1943, mainly due to World War II. After the war ended, the number of games returned to 11 games in
1946 and to 12 in 1947. The NFL went to a 14-game schedule in
1961, which it retained until switching to the current 16-game schedule in
 Proposals to increase the regular season to 18 games have been made, but have been rejected in labor negotiations with the
The NFL operated in a two-conference system from 1933 to
1966, where the champions of each conference would meet in the
NFL Championship Game. If two teams tied for the conference lead, they would meet in a
one-game playoff to determine the conference champion. In
1967, the NFL expanded from 15 teams to 16 teams. Instead of just evening out the conferences by adding the expansion
New Orleans Saints to the seven-member Western Conference, the NFL realigned the conferences and split each into two four-team divisions. The four division champions would meet in the
NFL playoffs, a two-round playoff.
 The NFL also operated the
Playoff Bowl (officially the Bert Bell Benefit Bowl) from 1960 to 1969. Effectively a
third-place game, pitting the two conference runners-up against each other, the league considers Playoff Bowls to have been
exhibitions rather than playoff games. The league discontinued the Playoff Bowl in 1970 due to its perception as a game for losers.
Following the addition of the former AFL teams into the NFL in
1970, the NFL split into two conferences with three divisions each. The expanded league, now with twenty-six teams,
 would also feature an expanded eight-team eight playoff, the participants being the three division champions from each conference as well as one 'wild card' team (the team with the best win percentage) from each conference. In 1978, the league added a second wild card team from each conference, bringing the total number of playoff teams to ten, and a further two wild card teams were added in
1990 to bring the total to twelve. When the NFL expanded to 32 teams in
2002, the league realigned, changing the division structure from three divisions in each conference to four divisions in each conference. As each division champion gets a playoff bid, the number of wild card teams from each conference dropped from three to two.