Ice hockey has been played for more than five hundred years, but the National Hockey League (NHL) has only been around since 1917. Formed by team owners in the aftermath of World War I (1914–18), this new professional league succeeded where previous ones, such as the International Pro Hockey League, the National Hockey Association, and the Pacific Coast League had failed.

The NHL originally consisted of five teams: the Montreal Canadiens, the Montreal Wanderers, the Ottawa Senators, the Quebec Bulldogs, and the Toronto Arenas. The league's first game was held December 19, 1917. By 1926, the league had expanded to ten teams and two divisions and adopted the Stanley Cup as its championship trophy. The financial shocks of the Great Depression (1929–41) claimed three of the franchises, while another folded in 1942, leaving the NHL a six-team league for the next twenty-five years. That period, from 1942 to 1967, saw increasing dominance of...