The 1891 major league baseball season was contested from April 8 through October 6, 1891. It was the final season for the American Association (AA), with the Boston Reds winning the AA pennant. In the National League (NL), in operation since 1876, the Boston Beaneaters won the NL pennant. There was no postseason. The Reds, following the 1890 Brooklyn Bridegrooms consecutive pennant wins 1889âÂÂ1890 in different leagues, also followed such a feat, winning the since folded Players' League's 1890 pennant and becoming the second and last team to win consecutive pennants in different leagues.
This was the first season since which saw no postseason, due to a breakdown in relations between the American Association and National League prior to the start of the season. The next championship series would take place the following season in a unique split season format, due to negotiations during the merger of the AA into the NL.
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 () 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). Each team was scheduled to play 20 games against the other seven teams of their respective league. This continued the format put in place by the American Association since the season and by the National League since the season, and was the last season this format would be used until the National League contracted from twelve to eight teams in .
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. The American Association would see its final day of the regular season on October 6, while the National would see its final day of the season on October 3.
The 1891 season saw the following rule changes:
An asterisk (*) denotes the ballpark a team played the minority of their home games at<br> A dagger (â ) denotes a team that folded mid-season<br> A double dagger (â¡) denotes a team joined mid-season
The Milwaukee Brewers hosted a neutral site game in Minneapolis, Minnesota against the Columbus Solons.
19 tie games (12 in AA, 7 in NL), which are not factored into winning percentage or games behind (and were often replayed again), occurred throughout the season.
Any team shown in indicates a previous team a player was on during the season.<br> Any team shown in italics indicates a team a player was on from a different league. Any stat from said different league is not calculated to determine the league leader.
Only records for National League teams are available.
The 1891 season saw five teams relocate to new ballparks, many of which were ballparks of the single-season Players' League the previous season:
The Chicago Colts begin playing at South Side Park, splitting their season from West Side Park. They would play their final game at West Side Park on October 2 against the Cincinnati Reds, permanently moving into South Side Park for the start of the season.
American Park, the home of the Cincinnati Reds, is renamed to League Park.
After the Cincinnati Outlaw Reds folded mid-season, the Milwaukee Brewers withdrew from the Western League as a replacement team, playing at Brewer Field. The team plays one of their 21 home games at a neutral site in Athletic Park in Minneapolis, Minnesota.