The National Hockey League up until the late 1960s were a six team league, just six franchises in the whole league representing two huge countries physically Canada and America. Spanning from the Atlantic to the Pacific oceans, until they expanded in the late 1960s in major markets like Philadelphia, Pittsburgh, Atlanta, St. Louis, Denver, Los Angeles, Washington in the mid 1970s. The National Hockey League spent its first fifty- years or so trying to prove to North America, especially America that they were even a major sports league, they've passed that test since, but they had a hard time expanding anywhere.
The NHL was reluctant to expand which is good reasons for the World Hockey Association. Not sure why they called it that because they were only in two countries, but it's good for major league hockey in North America that they came into business in the early 1970s. Because they proved in just seven seasons that major league hockey could work in both Canada and America and went into markets like Hartford, Cleveland, Quebec, Winnipeg, Denver, Edmonton and others. Giving pro hockey players more of a choice in where they could play in what league and for what team.
The WHA proved that major league hockey could work in North America that the NHL was trapping it's player in having to play for one team even after their contract expired. And that the NHL wasn't doing a very good job in attracting as many fans as they could. The WHA was able to do as well as they did in that brief seven-year window that they had because they were able to attract talent that should've been in the NHL. But that the NHL let slide away from them because again they were trying to keep them with one club not letting see for themselves what else was out there.
But also players that should've been in the NHL, but there just wasn't enough room for them because again up until the late 1960s again the NHL only had six clubs. Which meant great players like forwards Bobby Hull, Gordie Howe, Wayne Gretsky who I guess the NHL thought was too small. But all Wayne Gretsky did was show the world that he might be the best hockey player who ever played. But you could also make a case for Gordie Howe as far as who's the greatest all around hockey player of all-time, but thats a different debate.
And without the WHA maybe the NHL doesn't have thirty clubs today, because maybe they wouldn't of taken chances on markets like Nashville, Tampa, Miami, Raleigh, Denver, San Jose etc. And maybe they are still a small league just trying to survive like the Major Indoor Soccer League or something. The WHA was a success because a lot of their clubs were able to become part of the NHL. Like the Winnipeg Jets, Edmonton Oilers and others. And proved that major league hockey can succeed in North America. And without the WHA, the NHL is probably not as successful as it is today.