MLB organizational structure (1869 to present)
Major League Baseball (MLB) is the highest level of professional baseball in the United States and Canada, consisting of teams that play in the National League and the American League. The two leagues merged in 2000 into a single MLB organization led by the Commissioner of Baseball after 100 years as separate legal entities.MLB constitutes one of the major professional sports leagues of the United States and Canada. It is composed of 30 teams,29 in the United States and 1 in Canada. With the International Baseball Federation, MLB also manages the World Baseball Classic.