The Seattle Mariners joined the American League as an expansion team in 1977 playing their home games in the Kingdome. Since July 1999, the Mariners' home ballpark has been T-Mobile Park, located in the SoDo neighborhood of Seattle.
The "Mariners" name originates from the prominence of marine culture in the city of Seattle. They are nicknamed the M's, a title featured in their primary logo from 1987 to 1992. They adopted their current team colors – navy blue, northwest green (teal), and silver – prior to the 1993 season, after having been royal blue and gold since the team's inception. Their mascot is the Mariner Moose.
The organization did not field a winning team until 1991, and any real success eluded them until 1995 when they won their first division championship and defeated the New York Yankees in the ALDS. The game-winning hit in Game 5, in which Edgar Martínez drove home Ken Griffey Jr. to win the game in the 11th inning, clinched a series win for the Mariners, served as a powerful impetus to preserve baseball in Seattle, and has since become an iconic moment in team history.
The Mariners won 116 games in 2001, which set the American League record for most wins in a single season and tied the 1906 Chicago Cubs for the Major League record for most wins in a single season.
Through the end of the 2020 season, the franchise has finished with a losing record in 30 of 44 seasons. The Mariners are one of six Major League Baseball teams who have never won a World Series championship, and they are the only team to have never played in a World Series. They hold the longest playoff drought in all of the four major North American professional sports, having not qualified for the playoffs since their 116-win season in 2001.