More specifically, "Major League Baseball" (MLB) refers to the two top leagues, the National League and the American League, and the joint organizational structure which exists between them. MLB has a Commissioner, maintains joint umpiring crews, and negotiates marketing and television contracts for the two major leagues. This structure and the major league ownership of minor league baseball is possible because of an 1922 court decision in which baseball was ruled a local affair and not interstate commerce subject to antitrust law, an exemption which does not apply to other sports.
Current Major Leagues At the time of writing the Commissioner of Baseball, Bud Selig, has often floated the idea of further expansion and realignment of the major leagues. At the moment, however, the major leagues are each split into three divisions, and structured as follows:
|Anaheim Angels||Chicago White Sox||Baltimore Orioles|
|Oakland Athletics||Cleveland Indians||Boston Red Sox|
|Seattle Mariners||Detroit Tigers||New York Yankees|
|Texas Rangers||Kansas City Royals||Tampa Bay Devil Rays|
|Minnesota Twins||Toronto Blue Jays|
|Arizona Diamondbacks||Chicago Cubs||Atlanta Braves|
|Colorado Rockies||Cincinnati Reds||Florida Marlins|
|Los Angeles Dodgers||Houston Astros||Montreal Expos|
|San Diego Padres||Milwaukee Brewers||New York Mets|
|San Francisco Giants||Pittsburgh Pirates||Philadelphia Phillies|
|Saint Louis Cardinals|
Historical Major Leagues In 1969, the centennial of professional baseball, a commission chartered by Major League Baseball identified the following leagues as "major leagues". The list is sometimes disputed by baseball researchers. The MLB list included the following:
Some researchers contend that the National Association[?] (1871-1875), the Negro Leagues (primarily during the years from 1921-1946), and the first year of the American League (1900) deserve consideration as major leagues due to the caliber of player and the level of play exhibited. However, game and statistical records for these particular leagues were not kept in a consistent manner.