The 1899 major league baseball season was contested from April 14 through October 15, 1899, and saw the Brooklyn Superbas as the pennant winner of the National League. There was no postseason.
The 1899 was the final season of a stable 12-team, eight-season run which saw no expansion or contraction of teams. Following the end of the season, the National League contracted from 12 to 8 teams, eliminating the Baltimore Orioles, Cleveland Spiders, Louisville Colonels, and Washington Senators. The elimination of major-league baseball from these cities prompted the minor league Western League to position themselves as a major league in , by beginning a transition from a Midwest-focused league to the nationwide focused American League.
The 1899 season is famous for the Cleveland Spiders finishing with the worst single-season record of all time (minimum 120 games), finishing at a dismal (), largely due to the fact that the Spiders-owning Robison family bought the St. Louis Perfectos prior to the 1899 season, then proceeded to move all Cleveland talent to St. Louis, leaving the Spiders a talent-depleted team. The only other major-league team of the 19th century with a worse record was the 1884 Wilmington Quicksteps, who entered the unstable single-season Union Association as a late-season replacement for the Philadelphia Keystones and played only 18 games, with a record of ().
The Brooklyn Bridegrooms and St. Louis Browns renamed as the Brooklyn Superbas and St. Louis Perfectos, respectively.
The 1899 schedule consisted of 154 games for the twelve teams of the National League. Each team was scheduled to play 14 games against the other eleven teams in the league. This format had previously been used by the National League in and the previous season. This would be the final season which saw this format, due to the reduction of teams the following season.
Opening Day took place on April 14 featuring four teams. The final day of the season on October 15, featuring five teams play in four games (Chicago hosted Louisville and St. Louis hosted Chicago, while Cincinnati hosted Cleveland in a doubleheader).
The 1899 season saw the following rule changes:
Blue laws restricted Sunday activities in several localities, causing several teams to play at ballparks in a different locality.
20 tie games, which are not factored into winning percentage or games behind (and were often replayed again), occurred throughout the season.
The home of the St. Louis Perfectos, New Sportsman's Park, is renamed League Park.
The home of the Louisville Colonels, Eclipse Park, was destroyed in a fire on August 12, while the team was on a road trip. Following their return home, they would have a 12-game homestand from August 22 through September 2 in a partially rebuilt park, before spending the rest of the season on the road.
Regarding games that were rescheduled to Sunday, and existing blue laws: