The National Hockey League was organized on November 26, 1917, at the Windsor Hotel in Montreal after the suspension of operations of its predecessor organization, the National Hockey Association (NHA), which had been founded in 1909 in Renfrew, Ontario. The NHL immediately took the NHA's place as one of the leagues that contested for the Stanley Cup in an annual interleague competition before a series of league mergers and folds left the NHL as the only league left competing for the Stanley Cup in 1926.
At its inception, the NHL had four teams—all in Canada, thus the adjective "National" in the league's name. The league expanded to the United States in 1924, when the Boston Bruins joined, and has since consisted of American and Canadian teams. From 1942 to 1967, the league had only six teams, collectively (if not contemporaneously) nicknamed the "Original Six". The NHL added six new teams to double its size at the 1967 NHL expansion. The league then increased to 18 teams by 1974 and 21 teams in 1979. Between 1991 and 2000, the NHL further expanded to 30 teams. It added its 31st team in 2017 and has approved the addition of a 32nd team in 2021.
The league's headquarters have been in New York City since 1989 when the head office moved there from Montreal.
After a labour-management dispute that led to the cancellation of the entire 2004–05 season, the league resumed play in 2005–06 under a new collective agreement that included a salary cap. In 2009, the NHL enjoyed record highs in terms of sponsorships, attendance, and television audiences.
The International Ice Hockey Federation (IIHF) considers the Stanley Cup to be one of the "most important championships available to the sport". The NHL draws many highly skilled players from all over the world and currently has players from approximately 20 countries. Canadians have historically constituted the majority of the players in the league, with an increasing percentage of American and European players in recent seasons.
The current NHL champions are the St. Louis Blues, who defeated the Boston Bruins four games to three in the 2019 Stanley Cup Finals.
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