Happy 10th birthday to the SABR/Baseball-Reference Encyclopedia. Thanks to all those who have contributed and welcome to any who wish to contribute.
From BR Bullpen
A major league is a league that has be part of Major League Baseball throughout its history. Currently, it consists of the American League and National Leagues. In the past its has included the American Association, Union Association, and Players League in the 19th century, and the Federal League in the 20th century. It may also include the National Association of Professional Base Ball Players, a precursor to National League; however Major League Baseball does not recognize the league.