History of the National Hockey League/1967–1992/Rules and innovations
The early 1980s saw many tie games. The 1982–83 North Stars and Capitals both finished with 16 ties in 80 games, while 17 of 21 teams tied 10 or more games. The season before, the North Stars recorded 20 ties. As a result of the frequent ties, the NHL reintroduced overtime for the 1983–84 season. The effect was immediate, as only seven teams had ten or more ties. Before its discontinuation during World War II, the NHL played a full 10-minute overtime period. The modern overtime format was set as a five-minute, sudden death period; the game ended when either team scored.
The NHL changed its divisional alignment and playoff formats numerous times as it grew. The league's doubling in 1967 also led to the expansion of the playoffs to eight teams from four the previous year. Expansion to 18 teams in 1974 caused the league to realign into two conferences and four divisions, each named after important figures in league history. The teams were split into the Campbell Conference, consisting of the Patrick and Smythe divisions, and the Prince of Wales Conference, consisting of the Adams and Norris divisions. The playoffs were expanded to 12 teams, and each division winner was granted a bye in the first round of the playoffs. The addition of the four WHA teams in 1979 saw the playoffs expanded to 16 teams. Finally, in 1981, the league realigned all teams by geography. Eastern teams played in the Adams and Patrick divisions of the Wales Conference, and Western teams played in the Norris and Smythe divisions of the Campbell Conference. In addition, the playoff format was changed to have the top four teams in each division qualify rather than the top 16 teams overall. The first two playoff rounds were played entirely within each division. This format lasted until 1993.