The National League of Professional Baseball Clubs, known simply as the National League (NL), is the older of two leagues constituting Major League Baseball (MLB) in the United States and Canada, and the world's oldest current professional team sports league. Founded on February 2, 1876, to replace the National Association of Professional Base Ball Players, it is sometimes called the Senior Circuit, in contrast to MLB's other league, the American League, which was founded 25 years later. Both leagues currently have 15 teams. The two league champions of 1903 arranged to compete against each other in the inaugural World Series. After the 1904 champions failed to reach a similar agreement, the two leagues formalized the World Series as an arrangement between the leagues. National League teams have won 48 of the 113 World Series contested from 1903 to 2017.