Major professional sports leagues in the United States and Canada
The Canadian Football League is the highest level of play in Canadian football. The league was organized in 1956 as a cooperative agreement between two regional leagues, the Big Four (which dated to 1907) and the WIFU (which was founded in 1936), and became independent from Football Canada in 1958. The league now consists of nine teams, all based in Canada. The Grey Cup is awarded annually to the champion every November and is the highest attended sporting event in the nation. The oldest extant teams, the Hamilton Tiger-Cats and the Toronto Argonauts, trace their origins to the late 1860s and early 1870s, which ranks them amongst the oldest professional sports teams of any kind still in existence on the continent. The CFL attempted an expansion into the United States in cities that had no NFL team between 1993 and 1995, though the expansion teams all either folded or relocated to Canadian cities.
Canadian Football League
From the 1930s to the 1950s, the two senior leagues of the CRU, the eastern Interprovincial Rugby Football Union (IRFU or Big Four) and Western Interprovincial Football Union (WIFU) gradually evolved from amateur to professional leagues, and amateur teams such as those in the Ontario Rugby Football Union (ORFU) were no longer competitive for the Grey Cup. From 1945 onward, the WIFU's champion faced the Big Four's champion for the Grey Cup, though until 1954 it had to play in a semi-final against the champion of the ORFU–by then, the only amateur union still competing for the Grey Cup. The ORFU withdrew from Grey Cup competition after the 1954 season, and the WIFU champion was automatically awarded a berth in the Grey Cup final. For this reason, 1954 is reckoned as the start of the modern era of Canadian football, in which the Grey Cup has been exclusively contested by professional teams. Since 1965, Canada's top amateur teams, competing in what is now U Sports, have competed for the Vanier Cup.