Major League Baseball

Major League Baseball (MLB) is a professional baseball league. A total of 30 teams now play in two divisions, the American League (AL) and National League (NL), with 15 teams in each. The AL and NL operated as separate legal entities from 1901 and 1876 respectively, until 2000, when they were merged into a single organization known as Major League Baseball. After cooperating but remaining legally separate entities since 1903, in 2000 the leagues merged into a single organization led by the Commissioner of Baseball. The organization also oversees minor league baseball leagues, which comprise about 240 teams affiliated with the major-league clubs. With the World Baseball Softball Confederation, MLB manages the international World Baseball Classic tournament.

Baseball's first professional team was founded in Cincinnati in 1869. The first few decades of professional baseball were characterized by rivalries between leagues and by players who often jumped from one team or league to another. The period before 1920 in baseball was known as the dead-ball era; players rarely hit home runs during this time. Baseball survived a conspiracy to fix the 1919 World Series, which came to be known as the Black Sox Scandal. The sport rose in popularity in the 1920s, and survived potential downturns during the Great Depression and World War II. Shortly after the war, baseball's color barrier was broken by Jackie Robinson.