The American Association regular season ended on October 15 and saw the Louisville Colonels the winners of the AA pennant.
The Reds had floated a three-way Championship series with them and the AA & NL pennant winners, though the idea fell on deaf ears.
The American Association would see its final day of the regular season on October 15 with a doubleheader between the Baltimore Orioles and Rochester Broncos.
The National League would see its final day of the season on October 4, with a doubleheader between the Philadelphia Phillies and Cleveland Spiders.
The 1890 season saw the following rule change: A dagger (†) denotes a team that folded mid-season A double dagger (‡) denotes a team joined mid-season Blue laws restricted Sunday activities in several localities, causing several teams of the American Association (which was informally referred to as the "Beer & Whiskey League" due to its openness on alcohol, compared to the National and Players' Leagues) to play at ballparks in a different locality.