Major League Soccer (MLS) is a men's professional soccer league sanctioned by the United States Soccer Federation, which represents the sport's highest level in the United States. The league comprises 27 teams—24 in the U.S. and 3 in Canada—and plans to expand to 29 teams by the 2023 season. Although not one of the "Big Four", the MLS, along with the Canadian Football League, is considered one of the "Big Six" major professional sports leagues in the United States and Canada. The league is headquartered in Midtown Manhattan.