1903 Major League Baseball season

The 1903 major league baseball season began on April 16, 1903. The regular season ended September 29, with the Pittsburgh Pirates and the Boston Americans as regular season champions of the National League and American League, respectively. The postseason began with Game 1 of the first modern World Series on October 1 and ended with Game 8 on October 13. The Americans defeated the Pirates, five games to three.

The defunct Baltimore Orioles were replaced by a new franchise in New York City known as the New York Highlanders; it was the last change to the lineup of AL and NL franchises until. The Chicago Orphans and Cleveland Bronchos were renamed as the Chicago Cubs and Cleveland Naps, respectively.

Schedule
The 1903 schedule consisted of 140 games for all teams in the American League and National League, each of which had eight teams. Each team was scheduled to play 20 games against the other seven teams of their respective league. This continued the format put in place for the season. This would be the last season with this format, as the following season would see an increase of games played.

National League Opening Day took place on April 16 with four teams playing, while American League Opening Day did not take place until April 20, with a doubleheader between the Philadelphia Athletics and the Boston Americans. The National League would see its final day of the regular season on September 27, while the American League would see its final day of the season on September 29. The inaugural World Series took place between October 1 and October 13.

Rule changes
The 1903 season saw the following rule changes:
 * The pitcher's mound height was capped at 15 inches.
 * Previously adopted by the National league in, the American League adopted the rule that foul balls are to count as strike balls, except after two strikes. Previously, foul balls would not affect the count. To cut the cost of lost foul balls, the committee urges that batters who foul off good strikes are to be disciplined.

Bracket
 

"Battle of Ohio"
Termed the "Battle of Ohio", the Cincinnati Reds and Cleveland Naps played an unofficial best of 11-game exhibition series after the regular season, with Cleveland winning the series six games to three.

Events

 * August 1 – Joe McGinnity becomes the first pitcher to win two complete games in one day, with 4–1 and 5–2 victories for the New York Giants over the Boston Beaneaters in a doubleheader.