American League Championship Series

Prior to 1969, the American League champion (the "pennant winner") was determined by the best win–loss record at the end of the regular season.

There was one ad hoc single-game playoff held, in 1948, due to a tie under this formulation.

The ALCS started in 1969, when the AL reorganized into two divisions, East and West.

In 1981, a division series was held due to a split season caused by a players' strike.

The winners of that round then advanced to the best-of-seven ALCS; however, due to the player's strike later that season, no postseason was played and the new format did not formally begin until 1995.

Nine managers have led a team to the ALCS in three consecutive seasons; the record for most consecutive ALCS appearances by a manager is jointly held by Joe Torre, who led the New York Yankees to four in a row (1998, 1999, 2000, 2001), and Dusty Baker, who led the Houston Astros to four in a row (2020, 2021, 2022, 2023).