Title: Seattle Metropolitans
Content:  times between 1917 and 1920. The Metropolitans won the Stanley Cup in 1917, tied for the Cup in 1919 and lost in five games in 1920. The inspiring story of the Metropolitans' 1917 championship, making Seattle the first American team to win the Cup, was chronicled in the 2019 book, When It Mattered Most. Seattle's Stanley Cup championship occurred 11 years before the New York Rangers became the National Hockey League's first American franchise to win the Cup in 1928. The Metropolitans folded in 1924 when a replacement for the Seattle Ice Arena could not be found. Seattle would not have another team competing for the Stanley Cup for almost 100 years until the NHL expansion Seattle Kraken, who began play in 2021.
Title: Ice hockey in Seattle
Content:  Professional ice hockey in Seattle dates back to the formation of the Pacific Coast Hockey Association (PCHA)'s Seattle Metropolitans in 1915. The 1917 Metropolitans were the first United States-based team to win the Stanley Cup, but folded in 1924. The Seattle Totems played in the minor Western Hockey League (WHL) from 1944 until the WHL's dissolution in 1975. On October 26, 2021, the Seattle Kraken raised a banner commemorating the Metropolitans' 1917 title to the rafters of Climate Pledge Arena before the Kraken played against the Montreal Canadiens. The Canadiens had not played a game in Seattle since the 1919 Stanley Cup Finals, which were not completed due to the Spanish flu pandemic.
Title: Sports in Seattle
Content:  The city of Seattle has a total of 18 national championship honors, including one Stanley Cup, one NBA Championship, one Super Bowl Championship, four WNBA championships, four U.S. Open Cup championships, one MLS Supporters' Shield, two MLS Cup championships, two NWSL Shields and two MLR Championship Shields. Seattle's first professional sports championship was brought to the city by the Seattle Metropolitans in 1917, when they became the first American team to win the coveted Stanley Cup by beating the Montreal Canadiens three games to one. They returned to the Stanley Cup finals twice more. Their first return, again versus Montreal, was in 1919; that series was cancelled due to 
Title: Seattle Thunderbirds
Content:  most wins in team history (46), topping their record from the previous season. In the quarterfinal round of the 2016-2017 WHL playoffs, the Thunderbirds swept the Tri-City Americans, 4 games to 0, and advanced to the semifinal round for a rematch with Everett. The Thunderbirds continued their postseason domination of the Silvertips, sweeping the series 4 games to 0 to advance to the Western Conference Finals and yet another rematch with Kelowna. Although this series did not end in a sweep in Seattle's favor like the previous year, the Thunderbirds still prevailed over the Rockets, 4 games to 2. With the win, the Thunderbirds advanced to the 
Title: Ice hockey in Seattle
Content:  Ice hockey in Seattle includes professional teams as early as 1915, including the Seattle Metropolitans, the first United States-based team to win the Stanley Cup. Presently the city has a National Hockey League franchise, the Seattle Kraken, who began play in the 2021–22 season.
Title: Seattle
Content:  the start of the 20th century with the PCHA's Seattle Metropolitans, which in 1917 became the first American hockey team to win the Stanley Cup. Seattle was awarded a Major League Baseball franchise, the Seattle Pilots, in 1969. The team played at Sick's Stadium in Mount Baker for one season before relocating to Milwaukee and becoming the Milwaukee Brewers. The city, alongside the county and state governments, sued the league and was offered a second expansion team, the Seattle Mariners, as settlement. The Mariners began play in 1977 at the Kingdome, where the team struggled for most of its time. Finding success in the mid-to-late 1990s saved the 
Title: Sonics Arena
Content:  the home of the minor professional Western Hockey League Seattle Totems from 1963 to 1975. KeyArena was later home to the Seattle Thunderbirds of the major junior Western Hockey League from 1977 to 2009. In 2009, the Thunderbirds relocated to the ShoWare Center in nearby Kent. Several professional hockey teams have played in Seattle since 1915. The first was the Seattle Metropolitans, who played in the Seattle Ice Arena from 1915-1924 and became the first American team to win the Stanley Cup in 1917. Other professional hockey teams included the Seattle Eskimos, Seattle Ironmen, Seattle Bombers, and Seattle Americans. Climate Pledge Arena's current 
Title: Sports in Seattle
Content:  The Seattle Sounders (USL) won the A-League championship in 1995 and 1996 and the US First Division championship in 2005 and 2007. The Seattle SeaDogs defeated the Houston Hotshots two games to none for the Continental Indoor Soccer League championship in 1997. The Washington Stealth defeated the Toronto Rock 15–11 at Xfinity Arena in Everett for the National Lacrosse League Champion's Cup in 2010. The Seattle Sockeye won the USA Ultimate Club Championships in 2004, 2006, 2007, and 2019. They won the gold medal at the World Ultimate Club Championships (WUCC) in 1997 in Vancouver, British Columbia. They also won the 
Title: Sports in Seattle
Content:  national basketball championship trophy arrived in 2004, when the Seattle Storm defeated the Connecticut Sun two games to one to win the WNBA championship. The Seattle Storm won their second WNBA title in 2010, beating the Atlanta Dream in 3 games. Eight years later, the Storm swept the Washington Mystics in 2018 to take their third national championship. The team earned a fourth WNBA title in 2020 in a sweep against the Las Vegas Aces with all games played at a quarantined facility in Florida. The Seattle Mariners have won the American League West Pennant three times – in 1995, 1997, and, most recently, in 2001, after a record 
Title: Seattle Totems
Content:  After World War II, the Pacific Coast Hockey League (PCHL), a major professional league on the West Coast in the 1910s and 1920s, was resurrected as a semi-professional loop. Seattle, as a strong hockey town and notable for being the first city outside of Canada to host a Stanley Cup champion (the 1917 Seattle Metropolitans), was granted a franchise. The club had been founded as an amateur team the previous year, where they were known as the Seattle Isacsson Iron Workers, playing in the Northwest International Hockey League. When they entered the PCHL they were renamed the Seattle Ironmen. The club had modest success, finishing in first place in the league in 1948, while the league itself became fully professional in 1949. Its most notable stars were Gordon Kerr, the team's leading scorer in those years with 235 points in 244 games, William Robinson, Eddie Dartnell and Joe Bell. Among other notables for the team were future NHL star goaltender Al Rollins and legendary Philadelphia Flyers coach Fred Shero.

Question: when did seattle slew win the triple crown?
Answer: 1977.
in 1977.