| National Hockey League |
|
|
|
In: Montreal Canadiens
In: Montreal Wanderers
In: Ottawa Senators
In: Toronto Arenas
|
| 1917-18 |
4 Teams |
Out: Montreal Wanderers
|
|
| 1918-19 |
3 Teams |
Out: Toronto Arenas
|
In: Quebec Bulldogs
In: Toronto St. Pats
|
| 1919-20 |
4 Teams |
Out: Quebec Bulldogs
|
In: Hamilton Tigers
|
| 1920-21 |
4 Teams |
| 1921-22 |
4 Teams |
| 1922-23 |
4 Teams |
| 1923-24 |
4 Teams |
|
|
In: Boston Bruins
In: Montreal Maroons
|
| 1924-25 |
6 Teams |
Out: Hamilton Tigers
|
In: New York Americans
In: Pittsburgh Pirates
|
| 1925-26 |
7 Teams |
Out: Toronto St. Pats
|
In: Chicago Blackhawks
In: Detroit Cougars
In: New York Rangers
In: Toronto Maple Leafs
|
| 1926-27 |
10 Teams |
| 1927-28 |
10 Teams |
| 1928-29 |
10 Teams |
| 1929-30 |
10 Teams |
Out: Detroit Cougars
Out: Pittsburgh Pirates
|
In: Detroit Falcons
In: Philadelphia Quakers
|
| 1930-31 |
10 Teams |
Out: Ottawa Senators
Out: Philadelphia Quakers
|
|
| 1931-32 |
8 Teams |
Out: Detroit Falcons
|
In: Detroit Red Wings
In: Ottawa Senators
|
| 1932-33 |
9 Teams |
| 1933-34 |
9 Teams |
Out: Ottawa Senators
|
In: St. Louis Eagles
|
| 1934-35 |
9 Teams |
Out: St. Louis Eagles
|
|
| 1935-36 |
8 Teams |
| 1936-37 |
8 Teams |
| 1937-38 |
8 Teams |
Out: Montreal Maroons
|
|
| 1938-39 |
7 Teams |
| 1939-40 |
7 Teams |
| 1940-41 |
7 Teams |
Out: New York Americans
|
In: Brooklyn Americans
|
| 1941-42 |
7 Teams |
Out: Brooklyn Americans
|
|
| 1942-43 |
6 Teams |
| 1943-44 |
6 Teams |
| 1944-45 |
6 Teams |
| 1945-46 |
6 Teams |
| 1946-47 |
6 Teams |
| 1947-48 |
6 Teams |
| 1948-49 |
6 Teams |
| 1949-50 |
6 Teams |
| 1950-51 |
6 Teams |
| 1951-52 |
6 Teams |
| 1952-53 |
6 Teams |
| 1953-54 |
6 Teams |
| 1954-55 |
6 Teams |
| 1955-56 |
6 Teams |
| 1956-57 |
6 Teams |
| 1957-58 |
6 Teams |
| 1958-59 |
6 Teams |
| 1959-60 |
6 Teams |
| 1960-61 |
6 Teams |
| 1961-62 |
6 Teams |
| 1962-63 |
6 Teams |
| 1963-64 |
6 Teams |
| 1964-65 |
6 Teams |
| 1965-66 |
6 Teams |
| 1966-67 |
6 Teams |
|
|
In: Los Angeles Kings
In: Minnesota North Stars
In: Oakland Seals
In: Philadelphia Flyers
In: Pittsburgh Penguins
In: St. Louis Blues
|
| 1967-68 |
12 Teams |
| 1968-69 |
12 Teams |
| 1969-70 |
12 Teams |
Out: Oakland Seals
|
In: Buffalo Sabres
In: California Golden Seals
In: Vancouver Canucks
|
| 1970-71 |
14 Teams |
| 1971-72 |
14 Teams |
|
|
In: Atlanta Flames
In: New York Islanders
|
| 1972-73 |
16 Teams |
| 1973-74 |
16 Teams |
Out: California Golden Seals
|
In: California Seals
In: Kansas City Scouts
In: Washington Capitals
|
| 1974-75 |
18 Teams |
| 1975-76 |
18 Teams |
Out: California Seals
Out: Kansas City Scouts
|
In: Cleveland Barons
In: Colorado Rockies
|
| 1976-77 |
18 Teams |
| 1977-78 |
18 Teams |
Out: Cleveland Barons
|
|
| 1978-79 |
17 Teams |
|
|
In: Edmonton Oilers
In: Hartford Whalers
In: Quebec Nordiques
In: Winnipeg Jets
|
| 1979-80 |
21 Teams |
Out: Atlanta Flames
|
In: Calgary Flames
|
| 1980-81 |
21 Teams |
| 1981-82 |
21 Teams |
Out: Colorado Rockies
|
In: New Jersey Devils
|
| 1982-83 |
21 Teams |
| 1983-84 |
21 Teams |
| 1984-85 |
21 Teams |
| 1985-86 |
21 Teams |
| 1986-87 |
21 Teams |
| 1987-88 |
21 Teams |
| 1988-89 |
21 Teams |
| 1989-90 |
21 Teams |
| 1990-91 |
21 Teams |
|
|
In: San Jose Sharks
|
| 1991-92 |
22 Teams |
|
|
In: Ottawa Senators
In: Tampa Bay Lightning
|
| 1992-93 |
24 Teams |
Out: Minnesota North Stars
|
In: Anaheim Mighty Ducks
In: Dallas Stars
In: Florida Panthers
|
| 1993-94 |
26 Teams |
| 1994-95 |
26 Teams |
Out: Quebec Nordiques
|
In: Colorado Avalanche
|
| 1995-96 |
26 Teams |
Out: Winnipeg Jets
|
In: Phoenix Coyotes
|
| 1996-97 |
26 Teams |
Out: Hartford Whalers
|
In: Carolina Hurricanes
|
| 1997-98 |
26 Teams |
|
|
In: Nashville Predators
|
| 1998-99 |
27 Teams |
|
|
In: Atlanta Thrashers
|
| 1999-00 |
28 Teams |
|
|
In: Columbus Blue Jackets
In: Minnesota Wild
|
| 2000-01 |
30 Teams |
| 2001-02 |
30 Teams |
| 2002-03 |
30 Teams |
| 2003-04 |
30 Teams |
| 2005-06 |
30 Teams |
Out: Anaheim Mighty Ducks
|
In: Anaheim Ducks
|
| 2006-07 |
30 Teams |
| 2007-08 |
30 Teams |
| 2008-09 | 30 Teams |