The Canadian Football League was formed in 1956 when the two top Canadian football leagues in the country (the Interprovincial Rugby Football Union and Western Interprovincial Football Union) merged under one umbrella then known as the Candian Football Council (CFC). In 1958 the CFC separated itself from the governing Canadian Rugby Union and adopted the Canadian Football League name they still use today.
Several of the teams currently playing in the CFL pre-date the formation of the league due to this merger in 1956; the merging of the leagues led to two teams using the same nickname -- the Ottawa Rough Riders and Saskatchewan Roughriders until the Ottawa team folded in 1996.
The league played with the same eight teams until 1981 when the Montreal Alouettes folded, in 1993 the league expanded into the United States with the addition of the Sacramento Gold Miners. By 1995 the league had split into two divisions, one Canadian and one American, but following the season every American team either relocated or folded and the league returned to Canadian-only.