Four/three teams (1917–19)

The four teams that began the inaugural NHL season were the Montreal Canadiens, the Montreal Wanderers, the original Ottawa Senators, and the Toronto Arenas. However, after completing four games, the Wanderers withdrew from the league due to their arena burning down, and the NHL continued that season and the next with only three teams.

Four teams (1919–24)

In its third season, 1919–20, the NHL underwent its first expansion, adding the Quebec Bulldogs. Toronto changed its name to Toronto St. Patricks.

Six teams (1924–25)

Two new teams joined the NHL in its eighth season, the Boston Bruins and the Montreal Maroons, the first expansion team in the United States.

Seven teams (1925–26)

The next season, the NHL added two new teams, the Pittsburgh Pirates and the New York Americans. The Americans were stocked by purchasing the contracts of the Hamilton Tigers players, and the Tigers franchise was subsequently revoked by the league.

Ten teams (1926–31)

The NHL continued to expand the following 1926–27 season, adding the Chicago Black Hawks, the Detroit Cougars, and the New York Rangers, growing to ten teams, thus more than doubling its size in its first decade of existence. The league realigned into two divisions: the American Division and the Canadian Division. Despite its name, the Canadian Division contained at least one team based in the U.S. throughout its existence. At the same time, the Stanley Cup was contested between two NHL teams for the first time instead of outside league.

Midway through the 1926–27 season, the Toronto St. Patricks were sold and renamed the Toronto Maple Leafs, however the league ruled the team must use the St. Patricks name until season's end.

Eight teams (1931–32)

After fourteen seasons of steady expansion, the NHL contracted to eight teams, dropping the Philadelphia Quakers and the original Ottawa Senators for the 1931–32 season.

Nine teams (1932–35)

For the 1932–33 season, after missing one season, the original Ottawa Senators rejoined the NHL, and the Detroit Falcons were renamed the Detroit Red Wings.

Eight teams (1935–38)

The Eagles folded after one season, and the NHL was once again an eight-team league for three seasons.

Seven teams (1938–42)

The Montreal Maroons withdrew from the league for the 1938–39 season, further reducing the number of teams in the NHL to seven, shrinking to the size the league was in 1925–26. Play continued for four seasons with seven teams, with one single league table instead of any conference or divisions.

Twelve teams (1967–70)

The 1967 expansion doubled the number of teams in the league, with an upfront expansion fee of $2 million each ($18.3 million today).^[1] For the 1967–68 season, six new teams were added to the NHL: the California Seals, the Los Angeles Kings, the Minnesota North Stars, the Philadelphia Flyers, the Pittsburgh Penguins, and the St. Louis Blues.

Within a month into their first season, the California Seals became the Oakland Seals.

Fourteen teams (1970–72)

The Oakland Seals were renamed the Bay Area Seals for two games before changing their name again to the California Golden Seals for their fourth season in 1970–71. The same season the NHL added two new teams, the Buffalo Sabres and the Vancouver Canucks, paying an expansion fee of $6 million each ($47.1 million today).^[1] The Sabres and the Canucks were placed in the East (partially as an effort to provide greater balance between the divisions, and also so they would have rivalries with the other two Canadian teams), while the Chicago Black Hawks moved to the West.

Sixteen teams (1972–74)

Two more teams joined for the 1972–73 NHL season, the New York Islanders and the Atlanta Flames. With the competing World Hockey Association (WHA) starting that same season, the NHL was not able to raise its expansion fee from the price of two years earlier, $6 million ($43.7 million today), with the Islanders paying an additional $5 million ($36.4 million today) to the New York Rangers for infringing on their territory.^[2] The Islanders were placed in the East and the Flames were placed in the West.

Eighteen teams (1974–78)

Two more teams joined for the 1974–75 NHL season, the Washington Capitals and the Kansas City Scouts, but the ongoing competition from the WHA meant that the overall revenue stream of the NHL had not improved, so the league kept the expansion fee for new owners at the $6 million ($37.1 million today) of two years and four years earlier.^[2] The earnings situation for the new franchises was so poor that (at least) the Capitals were able to negotiate a reduction to a total fee of $2.85 million ($17.6 million today).^[2]

With 18 teams, the league realigned into four divisions and two conferences. The teams were mixed up regardless of North American geography, and thus the new conferences and divisions were not named after geographical references. The East Division became the Prince of Wales Conference and consisted of the Adams Division and Norris Division. The West Division became the Clarence Campbell Conference and consisted of the Patrick Division and Smythe Division.

1976: Two teams relocate

Going into the 1976–77 NHL season, the California Golden Seals relocated to become the Cleveland Barons, and the Kansas City Scouts moved to become the Colorado Rockies.

Seventeen teams (1978–79)

For the first time since the 1942–43 season, the NHL contracted, merging the Cleveland Barons into the Minnesota North Stars. The North Stars then took the Barons' place in the Adams Division.

Twenty-one teams (1979–91)

Following seven seasons of revenue draining competition, the NHL–WHA merger was completed for the start of the 1979–80 NHL season. Four teams came over from the WHA, paying an expansion fee of $7.5 million each ($31.5 million today).^[1] These new NHL teams were the Edmonton Oilers, Hartford Whalers, Quebec Nordiques, and the original Winnipeg Jets. This also doubled the number of Canadian teams in the league. Standing at 21 teams for twelve seasons, this was one of the longer periods of league stability, though surpassed by twenty-five seasons of the Original Six, when no additions, moves, nor name changes occurred.

The Nordiques were placed in the Adams Division, the Whalers in the Norris, and the Oilers and the Jets in the Smythe. The Washington Capitals moved from the Norris to the Patrick Division. The divisions were effectively meaningless as all teams played a balanced schedule and each round of the playoffs was re-seeded by league point standings rather than divisional.

1980: Flames relocate to Calgary

For the 1980–81 season, Atlanta relocated and became the Calgary Flames.

1981 realignment

For the 1981–82 season, the teams were realigned to reduce travel. Also, the Norris Division moved to the Campbell Conference and the Patrick Division moved to the Wales Conference.

1982: Colorado relocates to New Jersey

For the 1982–83 season, the Colorado Rockies moved, becoming the New Jersey Devils. The team was moved to the Patrick Division, while the Winnipeg Jets took their place in the Smythe Division.

1986: Chicago changes the spelling of its name

The Chicago Black Hawks changed their name to Chicago Blackhawks for the 1986–87 season.

Twenty-two teams (1991–92)

The 1991–92 season saw the addition of the San Jose Sharks, paying an expansion fee of $45 million ($100.7 million today).^[1] The Sharks were placed in the Smythe Division with the other West Coast teams.

Twenty-four teams (1992–93)

Two new teams joined the league the following season, the Ottawa Senators and the Tampa Bay Lightning, paying an expansion fee of $45 million each ($97.7 million today).^[1] The Senators were placed in the Adams Division, and the Lightning in the Norris, so all four divisions would have six teams each.

Twenty-six teams (1993–98)

The next season, another two teams were added, the Florida Panthers and the Mighty Ducks of Anaheim, paying an expansion fee of $50 million each ($105.5 million today), with Anaheim paying an additional $25 million ($52.7 million today) to the Los Angeles Kings for infringing on their region.^[1] The Minnesota North Stars relocated, becoming the Dallas Stars.

The league changed the conference names from Wales and Campbell to Eastern and Western, respectively, and changed the division names from Adams, Patrick, Norris, and Smythe to Northeast, Atlantic, Central, and Pacific, respectively.

Finally, the league realigned several teams. With the expansion Mighty Ducks joining the Pacific Division in the Western Conference, the original Winnipeg Jets left the Pacific for the Central, the Tampa Bay Lightning left the Central Division and Western Conference for the Atlantic and the Eastern, respectively, and the Pittsburgh Penguins left the Atlantic Division for the Northeast to make room for the expansion Florida Panthers.^[4]

1995: Nordiques relocate to Colorado

For the 1995–96 season, the Quebec Nordiques relocated and became the Colorado Avalanche. The team also switched conferences, moving from the Northeast Division in the East to the Pacific Division in the West.

1996: Jets relocate to Phoenix

The 1996–97 season, the original Winnipeg Jets moved, becoming the Phoenix Coyotes. The team remained in the Central Division.

1997: Whalers relocate to the Carolinas

The 1997–98 season saw the Hartford Whalers relocate, becoming the Carolina Hurricanes. The team remained in the Northeast Division.

Twenty-seven teams (1998–99)

The Nashville Predators joined the league for the 1998–99 season, paying an expansion fee of $80 million ($149.5 million today).^[1] The league also realigned to a strictly geographic six-division structure, with three per conference. The Eastern Conference had the Atlantic, Northeast, and Southeast divisions, while the Western Conference had the Central, Northwest, and Pacific divisions. The expansion Predators were placed in the Central Division. The Toronto Maple Leafs were the only team to switch conferences, moving from the Western to the Eastern and the Northeast Division, rejoining classic East Division and Adams Division rivals for the first time since the respective 1973–74 and 1980–81 seasons.

Twenty-eight teams (1999–2000)

The 1999–2000 season saw another team start play, the Atlanta Thrashers, paying the same expansion fee of $80 million ($146.3 million today) as the Predators a year earlier.^[1] The Thrashers were placed in the Southeast Division.

Thirty teams (2000–2017)

For its 2000–01 season, the NHL added the Columbus Blue Jackets and the Minnesota Wild, each paying the same expansion fee of $80 million ($141.5 million today) as Nashville and Atlanta in the previous two years.^[1] The Blue Jackets were placed in the Central Division and the Wild in the Northwest so all six divisions would each have five teams.

For the next 17 seasons, the NHL maintained 30 teams, the second longest period of membership stability in its history, the first being the Original Six.

2006: Anaheim shortens its name

The Mighty Ducks of Anaheim changed their name to the Anaheim Ducks in the 2006–07 season. The newly renamed Ducks would win the Stanley Cup that season.

2011: Thrashers relocate to Winnipeg

The Atlanta Thrashers moved to Winnipeg, Manitoba, becoming the second version of the Winnipeg Jets, beginning in the 2011–12 season. The team remained in the Southeast Division.

2013 realignment

The 2011 relocation of the former Atlanta Thrashers franchise to the Winnipeg Jets prompted the league to discuss realignment. However, disagreement between the NHL Board of Governors and the National Hockey League Players' Association (NHLPA) caused it to be pushed to 2013.

On December 5, 2011, the NHL Board of Governors originally approved a conference realignment plan to move from a six-division setup to a four-conference structure.^[5] However, on January 6, 2012, the National Hockey League Players' Association (NHLPA) rejected that proposed realignment.^[6][7] A new joint NHL-NHLPA plan was proposed in February 2013 as a modification of the previous plan with both the Columbus Blue Jackets and Detroit Red Wings moving to the East and the Winnipeg Jets moving to the West. The NHLPA officially gave its consent to the NHL's proposed plan on March 7,^[8] and then the NHL's Board of Governors approved the realignment on March 14, to be implemented prior to the 2013–14 season.^[9] The league then announced the names of the divisions on July 19: the two eight-team divisions in the Eastern Conference would be the Atlantic Division and the Metropolitan Division, and the two seven-team divisions in the Western Conference would be the Central Division and the Pacific Division.^[10]

2014: The Coyotes change their name

The Phoenix Coyotes changed their name to Arizona Coyotes for the 2014–15 season.

Thirty-one teams (2017–2021)

On June 22, 2016, the Board of Governors voted 30–0 to add an expansion franchise in Las Vegas for the 2017–18 season, charging an expansion fee of $500 million ($634.8 million today).^[1] The Vegas Golden Knights joined the Pacific Division of the Western Conference.

2020–21: COVID-19 pandemic

Due to the COVID-19 pandemic, which delayed the conclusion of the 2019–20 season and delayed and shortened the 2020–21 season, the NHL adopted a temporary divisional alignment for 2020–21. The primary considerations acknowledged by the league were the ongoing restrictions and quarantine requirements affecting the ability of its teams to cross the Canada–United States border. As a result, on December 20, 2020, the league announced it had temporarily suspended the Eastern and Western Conferences and realigned to four non-conference divisions: North, East, Central, and West. The North Division consisted of all seven Canadian teams and was the first all-Canadian division since the league first expanded into the United States in 1924. The regular season lasted 56 games and consisted solely of intra-divisional play.

Thirty-two teams (2021–2024)

On December 4, 2018, Seattle was announced as the location of a thirty-second franchise to begin play in the 2021–22 season, with an expansion fee of $650 million.^[11] The league reverted to its pre-COVID-19 divisions in 2021. Under the realignment of those divisions that was announced prior to the pandemic, the expansion Seattle Kraken were placed in the Pacific Division, while the Arizona Coyotes returned to the Central Division.^[11]

League expands to Utah, Coyotes suspend operations (2024–present)

On April 18, 2024, the Arizona Coyotes were deactivated, and its players and personnel were transferred to a new expansion team in Utah. The Coyotes franchise would be reactivated if a suitable arena is built in Arizona; if not, the Coyotes will cease operations.^[12]