National Football League

The National Football League (NFL) is a professional American football league in the United States. Composed of 32 teams, it is divided equally between the American Football Conference (AFC) and the National Football Conference (NFC). The NFL is one of the major professional sports leagues in the United States and Canada and the highest professional level of American football in the world. Each NFL season begins annually with a three-week preseason in August, followed by the 18-week regular season, which runs from early September to early January, with each team playing 17 games and having one bye week. Following the conclusion of the regular season, seven teams from each conference, including the four division winners and three wild card teams, advance to the playoffs, a single-elimination tournament, which culminates in the Super Bowl, played in early February between the winners of the AFC and NFC championship games. The NFL is headquartered in Midtown Manhattan.

The NFL was formed in 1920 as the American Professional Football Association (APFA) before renaming itself the National Football League for the 1922 season. After initially determining champions through end-of-season standings, a playoff system was implemented in 1933 that culminated with the NFL Championship Game until 1966. Following an agreement to merge the NFL with the rival American Football League (AFL), the Super Bowl was first held in 1967 to determine a champion between the best teams from the two leagues and has remained as the final game of each NFL season since the merger was completed in 1970. The NFL is the wealthiest professional sports league in the world by revenue, and the sports league with the most valuable teams. The NFL also has the highest average attendance (67,591) of any professional sports league in the world and is the most popular sports league in the United States. The Super Bowl is also among the most-watched sporting events in the world, with the individual games accounting for many of the most watched television programs in American history and occupying the top five of Nielsen's all-time most-watched U.S. television broadcasts by 2015.

The Green Bay Packers hold the most combined NFL championships with thirteen, winning nine titles before the Super Bowl era and four Super Bowls afterwards. Since the creation of the Super Bowl, the New England Patriots and Pittsburgh Steelers are tied for the most Super Bowl victories at six each. The reigning league champions are the Philadelphia Eagles.

On August 20, 1920, a meeting was held by representatives of the Akron Pros, Canton Bulldogs, Cleveland Indians, 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".

A second meeting was held on September 17, 1920, with representatives from teams within four states: Akron, Canton, Cleveland, and Dayton from Ohio; the Hammond Pros and Muncie Flyers from Indiana; the Rochester Jeffersons from New York; and the Rock Island Independents, Decatur Staleys, and Racine (Chicago) Cardinals from Illinois. The league was renamed to the American Professional Football Association (APFA). The league elected Jim Thorpe as its first president, and consisted of 14 teams (the Buffalo All-Americans, Chicago Tigers, Columbus Panhandles and Detroit Heralds joined the league during the year). The Massillon Tigers from Massillon, Ohio was also at the September 17 meeting, but did not field a team in 1920. Only two of these teams, the Decatur Staleys (now the Chicago Bears) and the Chicago Cardinals (now the Arizona Cardinals), remain in the NFL.

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 record. The first event occurred on September 26, 1920, when the Rock Island Independents defeated the non-league St. Paul Ideals 48–0 at Douglas Park. 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 Buffalo All-Americans. On June 24, 1922, the APFA changed its name to the National Football League (NFL).

In 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. The 1934 season also marked the first of twelve seasons in which African Americans were absent from the league. 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 largest professional football league in the United States; it nevertheless faced numerous rival professional leagues through the 1930s and 1940s. Rival leagues included at least three separate American Football Leagues and the All-America Football Conference (AAFC), on top of various regional leagues of varying caliber. Three NFL teams trace their histories to these rival leagues; the Los Angeles Rams who came from a 1936 iteration of the American Football League, and the Cleveland Browns and San Francisco 49ers, both 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 Canadian football circuit, which formally became the Canadian Football League (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.