What year did the NHL expand to 12 teams?

Answer 1

The NHL expanded from six teams to twelve teams in 1967 by adding the following teams, which all began play at the start of the 1967-68 season:

• Philadelphia Flyers
• Pittsburgh Penguins
• St. Louis Blues
• Minnesota North Stars (moved to Dallas and became the Dallas Stars prior to the 1993-94 season)
• Los Angeles Kings
• California Seals (moved to Cleveland and became the Cleveland Barons prior to the 1976-77 season; merged with the Minnesota North Stars prior to the 1978-79 season)

Answer 2

The NHL expanded from 6 teams following the 1966-1967 season.

Commencing in the Fall of '67, teams from Minnesota, St. Louis, Los Angeles,

Oakland, Pittsburgh and Philadelphia entered the league.