MLS, founded in the United States, is a fully professional league with 26 teams, three of which are based in Canada, and is the top soccer league in both countries. Referees are approved by the United States Soccer Federation and Canadian Soccer Association, which run the sport in the two countries. In turn, U.S. Soccer and the CSA are members of FIFA, which governs all play between national teams and sets the rules for the sport along with the national governing bodies of England, Northern Ireland, Scotland, and Wales.