History of organizational changes in the NHL
In 1979, the World Hockey Association (WHA) ended and four teams from the league joined the NHL. They were the Edmonton Oilers, the New England Whalers (who became the Hartford Whalers after joining the league), the Quebec Nordiques and the Winnipeg Jets. At this point, the NHL had three Canadian teams, but with three of the teams coming from the WHA being Canadian, there were then twice as many Canadian teams as before.