National League

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 extant professional team sports league. Founded on February 2, 1876, to replace the National Association of Professional Base Ball Players (NAPBBP) of 1871–1875 (often called simply the "National Association"), the NL is sometimes called the Senior Circuit, in contrast to MLB's other league, the American League, which was founded 25 years later and is called the "Junior Circuit". Each league has 15 teams.

The National League survived competition from various other professional baseball leagues during the late 19th century. Most did not last for more than a few seasons, with a handful of teams joining the NL once their leagues folded. The American League declared itself a second major league in 1901, and the AL and NL engaged in a "baseball war" during 1901 and 1902 before agreeing to a "peace pact" that recognized each other as legitimate "major leagues". As part of this agreement, the leagues agreed to respect player contracts, establish rules about relationships with minor league clubs, and allow their champions to meet in a "World Series" to decide the overall professional baseball championship. National League teams have won 53 of the 121 World Series championships contested from 1903 to 2025.