Professional football in Canada
Only one professional football league has a permanent presence in Canada: the Canadian Football League (CFL), an organization founded in 1958 to accommodate the ongoing trend of professionalism in the Canadian football ranks since the 1940s. The CFL, like most amateur Canadian football leagues, plays on a larger field using a rulebook with several significant rule differences compared to the game as it is played in the United States. The league is composed of two divisions and nine teams in most of the largest Canadian markets, with at least one team in each province between British Columbia (BC Lions) and Quebec (Montreal Alouettes) inclusive. The only presence in Atlantic Canada is a semi-regular series of games in Moncton (Touchdown Atlantic) and a smattering of earlier preseason contests. The CFL operates a two-week preseason beginning in June, an 18-game season from July to October, and a six-team playoff tournament, culminating in the Grey Cup on the fourth weekend of November.
National Football League
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 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, 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 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.