This was done in order to keep teams of similar competitive strength in the same division, regardless of geographic distance,[1] and to ensure playoff revenue for the new franchises.
When the NHL expanded again in 1970, the two new teams, the Vancouver Canucks and Buffalo Sabres, were placed into the stronger East Division.
In an effort to create more balanced competition, the Chicago Black Hawks were transferred into the West Division.
The East and West Divisions were renamed the Prince of Wales and Clarence Campbell Conferences, respectively, composed of nine teams each.
The East and West Divisions were re-formed for the 2020–21 season as the result of the COVID-19 pandemic which forced the NHL to radically re-structure the League and to temporarily abolish the conferences.