the merger of a rival league. Only one team in the National Hockey League (the Montreal Canadiens), for example, existed before becoming part of the NHL. The rest of the teams were created ex novo as expansion teams or as charter members of the World Hockey Association, which merged with the NHL in 1979. American and Canadian sports leagues typically have a "playoff" system where the best teams in a given season compete in a tournament, with the winner being crowned champion of the league for that season. These have their roots in the long travel distances common in US and Canadian sports; to cut down on travel, leagues are typically divided into geographic divisions and feature unbalanced schedules with teams playing more matches against opponents in the same division. Due to this, not all teams face the same opponents, and some teams may not meet during a regular season at all. This results in teams with identical records that have faced different opponents differing numbers of times, making team records alone an imperfect measure of league supremacy. Major League Soccer is technically not an association of franchises but a single business entity, though each team has an owner-operator; the team owners are actually shareholders in the league. The league, not the individual teams, contracts with the players. Unlike teams in the four traditional major North American sports leagues, MLS teams play meaningful games against teams from other nations. The MLS season serves as a qualifier for the CONCACAF Champions League, featuring teams from throughout the northern half of the Americas, including the Caribbean. Starting in 2023, all MLS teams play in the Leagues Cup, a competition also involving all sides in Mexico's top flight of Liga MX that serves as an additional qualifier for the Champions League. Also, MLS uses playing rules set by the international governing body of its sport. MLS followed its own playing rules until 2004, when it adopted FIFA rules. Under the auspices of US Soccer and the Canadian Soccer Association, respectively, the U.S. and Canada have separate knockout cup competitions during the MLS season that include teams from lower leagues. In the U.S., the U.S. Open Cup has had MLS participation from the league's inception; since the 2012 cup, each competition has featured all American-based MLS sides. Similarly, all of Canada's MLS teams compete in the Canadian Championship. However, the league structure of MLS