The CFL has existed since 1958. Prior to that, it's original teams played predominantly in the Interprovincial Rugby Football Union ("Big Four") of the East, and the Western Interprovincial Football Union of the West. These two Unions would eventually break off from the Canadian Rugby Union and form the two divisions of the CFL. The oldest CFL team is the Toronto Argonauts, who are the oldest active professional sports team in North America. They will celebrate their 150th anniversary in 2023, having been founded on October 4th, 1873.