what mlb team play in in
- For other uses, see MLB (disambiguation). Major League Baseball (MLB) is a professional baseball organization, the oldest of the four major professional sports leagues in the United States and Canada. A total of 30 teams now play in the National League (NL) and American League (AL), with 15 teams in each league. The NL and AL operated as separate legal entities from 1876 and 1901 respectively.