MLB fused two rival leagues after the 1903 National Agreement
Major League Baseball fields thirty clubs—fifteen National, fifteen American—with twenty-nine in the U.S. and one in Canada. The NL (1876) and AL (1900) warred over contracts until the 1903 peace that framed modern majors. Dead-ball days and the 1919 Black Sox fix remade governance.
Civil War camps helped nationalize New York–style baseball; the amateur NABBP gave way to pro associations, then the 1876 National League emphasizing clubs over player freedom. Expansion waves in the 1960s grew the map; labor fights against the reserve clause birthed the players’ union era. The NABBP had more than 400 member clubs by 1867 and allowed paid players from 1869, the year the Cincinnati Red Stockings turned fully professional; the Chicago Cubs and Atlanta Braves trace their roots to the professional association formed in 1871.
By revenue MLB ranks among the world’s richest leagues, recently behind the NFL and, as of 2026 figures cited, the NBA. Broadcasts span TV, radio, and streaming. In 2025 it drew 71.4 million spectators, the largest season attendance of any league anywhere.
Each club plays 162 games from late March or early April, and six teams per league reach an October playoff ending in the best-of-seven World Series, first staged in 1903. The two leagues stayed legally separate until 2000, when they merged under the commissioner, an office created after the Black Sox affair to replace the weak National Commission. Unlike rival sports, baseball lost no teams during the Depression or World War II, and Jackie Robinson broke its colour barrier soon after the war.
Artificial turf changed play in the 1970s and 1980s, home runs dominated the 1990s, and the 2006–07 Mitchell Report found steroid use on every team. The New York Yankees hold a record 27 titles, and the Los Angeles Dodgers beat the Toronto Blue Jays in the 2025 World Series.
Source: Major League Baseball
