Longest game in major league history
From BR Bullpen
The longest game, by time, in major league history was played on May 8 and 9, 1984 in Chicago. The Milwaukee Brewers and Chicago White Sox played seventeen innings on May 8 before the game was suspended with the score 3-3.
The next day, the game was resumed before the regularly scheduled game. In the 21st inning, it appeared the Brewers would win after Ben Oglivie hit a three run homer. The White Sox answered with three runs of their own, two of them on a Tom Paciorek single. The game continued into the 25th inning.
In the home half of the 25th, with one out, White Sox outfielder Harold Baines homered on the 753rd pitch of the game. The homer gave the Sox a 7-6 win. It also set the record for the latest in a game a player has slugged a home run. Carlton Fisk also set a record by catching all 25 innings.
Also notable, Tom Seaver won the game in relief for the Sox then started the regular game and threw another 8 1/3 innings to get two of his 311 career wins on the same day.
The game set a record for elapsed time, a total of 8 hours, 6 minutes. It was not the longest game for innings, as that was the famous 1-1 tie in which Leon Cadore and Joe Oeschger matched zeroes for 26 innings in 1920.