For many years after the shakeout caused by the Depression and World War II, the NHL owners staunchly resisted applications to expand beyond the so-called "Original Six" clubs (Boston Bruins, Montreal Canadiens, Toronto Maple Leafs, New York Rangers, Detroit Red Wings and Chicago Blackhawks). Groups representing Philadelphia (which had secured rights to the dormant Montreal Maroons franchise), Los Angeles and the AHL Cleveland Barons were each in turn given conflicting requirements that seemed to contemporary observers designed to disqualify the bids, and it was widely understood that the existing NHL owners wanted no encroachments upon their profits.
The NHL had been an early leader in television broadcasting, both in Canada and the U.S. However, by 1960, its TV contracts had expired, and the league had none until 1963. The owners saw that the televising of other sports had enhanced the images of those leagues' players, and feared that this would provide leverage at salary time. Already, players were starting to get legal help in negotiating contracts. Additionally, the league did not want to change game start times to suit the networks. In 1965, the NHL was told that it would not receive a U.S. television contract without expansion, and that the networks were considering televising games from the Western Hockey League, an ostensibly minor league that had, by that time, expanded into several large West Coast markets and accumulated strong rosters of players excluded from the static NHL lineups of the era. Because of this, and a generally favorable environment for alternative sports leagues (the American Football League had become a rousing success around the same time, while the abortive Continental League nonetheless had a role in the expansion of baseball), the NHL's control over major professional hockey was legitimately threatened.
Fears of the WHL becoming a rival major league, and the desire for a lucrative TV contract in the U.S. much like the ones Major League Baseball and the National Football League had secured, wore down the opposition; moreover, as more conservative owners retired, a younger guard more receptive to expansion, such as Stafford Smythe in Toronto, David Molson in Montreal, and William M. Jennings in New York, took power.
In 1963, Rangers governor William Jennings introduced to his peers the idea of expanding the league to the American West Coast by adding two new teams for the 1964–65 season. His argument was based around concerns that the Western Hockey League intended to operate as a major league in the near future. He also hoped that teams on the west coast would make the league truly national, and improve the chances of returning to television in the United States as the NHL had lost its deal with CBS. While the governors did not agree to the proposal, the topic of expansion came up every time the owners met from then on out.
The expansion process formally began in March 1965, when NHL President Clarence Campbell announced that the league proposed to expand its operations through the formation of a second six-team division. San Francisco – Oakland and Vancouver were declared "acceptable cities" with Los Angeles and St. Louis as potential sites. In February 1966, the NHL Board of Governors considered applications from 14 different ownership groups, including five from Los Angeles, two from Pittsburgh, and one each from Minneapolis – Saint Paul, Philadelphia, San Francisco – Oakland, Baltimore, Buffalo and Vancouver. Cleveland and Louisville had also expressed previous interest but were not represented.
Six franchises were ultimately added: the California Seals (San Francisco – Oakland), Los Angeles Kings, Minnesota North Stars, Philadelphia Flyers, Pittsburgh Penguins, and the St. Louis Blues. Had one of the teams been unable to start, a franchise would have then been awarded to Baltimore.
Canadian fans, including Prime Minister Lester Pearson, were irate that no Canadian teams were added, particularly since Vancouver had been generally considered a lock for a team. Internal considerations took a hand in this, as Montreal and Toronto were not interested in sharing CBC TV revenues with another Canadian club, and Chicago owner Arthur Wirtz's support was reputedly contingent on the creation of a St. Louis team – though no formal bid had actually been received from St. Louis – to purchase the decrepit St. Louis Arena, which the Black Hawks ownership then also owned.
On a more general note, many traditionalists resisted expansion, claiming it would dilute the talent in the league. Even some of the proponents of expansion were worried at the idea of immediately doubling the NHL's size, instead of easing teams in gradually, as Major League Baseball was doing.
The expansion fee was US$ 2 million, and players taken in the very strict expansion draft came at a cost of $50,000 each. Experts tended to see this as high, and most expansion teams were seen as having no hope of competing successfully with the established teams in the near future.
Due to the inherent competitive imbalance, there was some support for the idea of placing the new teams in a completely separate division or conference, with a separate schedule for the first few seasons, and then gradually integrating the new teams into the established NHL, much like the then-progressing AFL-NFL merger was being carried out. Ultimately, the league partly implemented this idea by placing all six of the new teams in the newly formed West Division. A more geographically appropriate alternative proposal to put Detroit and Chicago in the West with Pittsburgh and Philadelphia going to the East was rejected. In a surprising concession, the league also agreed to implement a strictly divisional playoff bracket, meaning that four expansion teams would make the playoffs and an expansion team was guaranteed a slot in the Stanley Cup Finals.
The new teams offered a big change to the league. After seeing virtually the same red/blue/black uniforms for over twenty years, purple, green, sky blue, and orange were introduced. Teams now regularly travelled between cities by air due to the distances involved; at the time, all of the Original Six cities had daily overnight passenger rail service between each other.
The 1967 expansion marked the end of the Original Six era and the beginning of a new era of the NHL. The expansion, Bobby Orr's record $1 million contract in 1971, and the formation of the World Hockey Association (WHA) in 1972 forever changed the landscape of the North American professional game. It was the WHA that ended up being the NHL's chief rival during the 1970s, while the Western Hockey League ceased operations in 1974. The NHL would later expand to 18 teams by 1974, and then merge with the WHA in 1979. As a result, the NHL retained its status as the premier professional ice hockey league in North America; no other league has successfully competed against the NHL since then.
However, the NHL's other goal of immediately securing a lucrative TV contract in the U.S. similar to MLB and the NFL never fully materialized until decades later. Despite the expansion and the subsequent merger with the WHA, NHL broadcasting on a national scale in the U.S. still continued to be spotty between 1967 and 1981; NBC and CBS held rights at various times, but neither network carried anything close to a full schedule, even carrying only selected games of the Stanley Cup Finals. And from 1971 to 1995, there was no exclusive coverage of games in the United States; although national cable channels like ESPN and the USA Network televised NHL games during this period, local broadcasters could also still televise them regionally as well. It was not until 1995 that Fox signed on to be the exclusive national broadcast network for a full schedule of regular season and playoff games, as well as selected games of the Cup Finals.
All the 1967 expansion teams were placed in the same division in 1967–68, so their success was largely gauged relative to each other before the 1974 realignment, which radically mixed up all of the league's teams into four divisions and two conferences. Subsequent expansions and realignments separated both the Original Six and the 1967 expansion teams even further, essentially reviving the league's earlier alternative plan to put Detroit and Chicago in the West, and Pittsburgh and Philadelphia in the East. After the 1998 realignment, which reorganized the league into six divisions, only the Flyers and the Penguins are in the same division. When the league realigned again in 2013, the Stars and Blues were placed in the same division.
The St. Louis Blues immediately made an impact, making three Stanley Cup Finals appearances in the first three years, but were swept on all three occasions, and have not reached the Cup Finals since then.
After the 1969–70 season, the league moved Chicago to the West Division and altered the playoff format to force Eastern and Western teams to face each other prior to the final. It would not be until 1974 when an expansion team would best an Original Six team in a playoff series or reach the Final again. That season, the Philadelphia Flyers, who had steadily built a strong team, would go on to defeat Boston to win the Stanley Cup. They would repeat as champions in 1975 by defeating the Buffalo Sabres in the first modern Stanley Cup Final to not feature an Original Six club. As of the end of the 2011–12 season, which marked the 44th season for the 1967 expansion teams, the Flyers are the most successful in terms of all-time points percentage (.579) – second only to the Montreal Canadiens (.588) in NHL history. Additionally, the Flyers have the most appearances in the league semi-finals (known as the conference finals since the 1981–82 season) out of all 24 expansion teams (16), the most Stanley Cup Finals appearances (8), and they are tied with St. Louis Blues for the most playoff appearances out of all the expansion teams (36 out of 44 seasons).
The Pittsburgh Penguins were largely unsuccessful in the beginning, failing to win their division until the 1990–91 season, but accumulated draft picks and built a strong team that would win two consecutive Stanley Cups in 1991 and 1992. In 2009, the Penguins became the first of the 1967 expansion teams to win three Cups. Then in 2016, Pittsburgh tied the New York Rangers (an Original Six team) and the New York Islanders (a 1972 expansion team) with four Cups. Only the Edmonton Oilers (with five Cups) have more Cups among all non-Original Six teams, with the Oilers joining the league in the 1979 merger with the WHA.
The Los Angeles Kings did not make a Stanley Cup Finals appearance until 1993 during the Wayne Gretzky era. The Kings did not return to the Cup Finals again until 2012, when they finally won their first Cup. Los Angeles won the Cup again in 2014.
While four of the 1967 expansion teams still play in their original cities, one has relocated and one ceased operations. Despite being in a traditional hockey area bordering Canada to the north, the Minnesota North Stars struggled financially for much of their time in Minnesota. They did manage to make two finals appearances in 1981 and 1991, but ended up moving to Dallas, Texas, in 1993 to become the Dallas Stars, eventually winning their first Cup in 1999. The NHL would return to Twin Cities market when the Minnesota Wild began play in 2000.
The Oakland/San Francisco Bay Area-based franchise was the least successful of the 1967 expansion teams: noncompetitive both on the ice and at the box office, the club eventually moved to Cleveland to become the Barons in 1976, and then merged with the Minnesota North Stars in 1978. Gordon and George Gund III, who acquired minority ownership of the Seals in 1974 and held it throughout the team's tenure in Cleveland and its merger with Minnesota, then asked the NHL for permission to move the North Stars to the Bay Area in the late 1980s. Instead, the league eventually awarded them a new franchise for the Bay Area: the San Jose Sharks, which began play in 1991.
For the 2016–17 NHL season, the four "expansion six" teams still in their original cities will have festivities commemorating their 50th year in the NHL and each unveiled uniform patches to be worn by those teams. The existing Stars franchise in Dallas is trying to figure out how to properly honor their fore-bearers in Minnesota while coordinating it with the Wild, while it is not known if the Sharks will honor the Seals past. The Seals/Barons successors in Ohio, the Columbus Blue Jackets, have no plans to participate in the festivities.
The patches were unveiled on February 9, 2016, on the 50th anniversary of the NHL awarding the franchises, which led the Penguins to unveil a patch with three Stanley Cups. With the Penguins winning that year's Stanley Cup Finals, their patch will be modified to have four Cups.
Among the six 1967 expansion teams, four still play in their original cities. One has since relocated and one ceased operations; both were eventually replaced in those areas with new teams.