The 1891 season saw the aftermath of the single-season Players' League disbanding during the offseason, with most teams either folding or merging with existing American Association and National League teams; the Boston Reds and Philadelphia Athletics would join the AA for the 1891 season, with the latter replacing the financially struggling original AA Philadelphia Athletics.
The unstable American Association would see that 1891 would be its final season, before merging into the National League the following season; the four clubs that would continue on were the Baltimore Orioles, Louisville Colonels, St. Louis Browns, and Washington Statesmen.
The other four AA clubs, the Boston Reds, Columbus Solons, Milwaukee Brewers, and Philadelphia Athletics), saw their owners paid $135,000 (equivalent to $4,578,000 in 2023) and their players dispersed to the surviving twelve clubs.
The 1891 schedule consisted of 140 games for all teams in the American Association and National League, each of which had eight active teams (the Milwaukee Brewers would finish the Cincinnati Kelly's Killers' schedule once they folded following their last game on August 16).
American Association Opening Day took place on April 8 featuring all eight teams, while National League Opening Day would not take place for another two weeks on April 22, also featuring all eight teams.