What's the longest inning in MLB history?

The longest game that ever played in the baseball in history is listed below:

Home team: Brooklyn Dodgers
Visitors: Boston Braves
Date: May 01 1920
Innings: 26

The game was called due to darkness, as they didn't have lights way back then, resulting in a 1 - 1 tie and going down in history as the longest game by innings.

Also, there's a current game just about 20 years ago that came close to the one above:

Home team: Chicago White Sox
Visitors: Milwaukee Brewers
Date: May 09 1984
Innings: 25
Length: 8 hours & 6 minutes

The game began on May 08 but according to MLB rules an inning cannot begin after 12:59 AM so the players and fans had to come back the next day.

The overall game time was 8 hours 6 minutes with Chicago finally winning 7- 6 on Harold Baines' home run in the 25th inning, one inning short of the record, but still the longest game based on time.