Alexander Cartwright, the father of modern baseball rules

Early Baseball Leagues History

In 1845, Alexander Cartwright led the establishment of the Knickerbocker Base Ball Club, the first team believed to have played baseball under modern rules. The club's by-laws committee formulated the Knickerbocker Rules, which in large part dealt with organizational matters and laid out rules for playing the game. (read more)

League championships were typically awarded to the the team with the best regular-season record. In 1876, the top 2 NL teams agreed to play a 5-game Championship of the West. From 1884-1891, the NL and AA met in a World's Championship Series. The NL has tried several championship formats: a playoff series in 1892 between half-season champions, a best-of-7 Temple Cup series from 1894-1897, and a Chronicle-Telegraph Cup series in 1900. Since 1903, the AL and NL champions meet annually in the World Series to determine a champion.
Logo for Federal League
FL: 1913-1915 (3 seasons)

Eliminated the 'reserve clause', allowing free agency that created competition and disdain with the AL and NL.

Logo for United States Baseball League
USBL: 1912-1913 (2 seasons)

Sputtering through two short seasons, the league was the first to introduce free agency and multi-year contracts.

Logo for American League
AL: 1901- (119 seasons)

The "Junior Circuit" claimed Major League status 25 years after the formation of the NL.

Logo for Western League
WL: 1894-1900 (7 seasons)

Originally a minor league in 1885, evolved into a major league that eventually became the modern American League.

Logo for Players League
PL: 1890-1890 (1 season)

Known as "The Brotherhood" league, it was formed around players from the National League's first players' union.

Logo for Union Association
UA: 1884-1884 (1 season)

The league president's favoritism toward his own St. Louis franchise doomed the league from the beginning.

Logo for American Association
AA: 1882-1891 (10 seasons)

Became a significant force in baseball by playing on Sundays and allowing sales of alcohol, unlike the NL.

Logo for National League
NL: 1876- (144 seasons)

The "Senior Circuit" is the world's oldest professional team sports league still in existence today.

Logo for National Association
NA: 1871-1875 (5 seasons)

The league included most of the pro clubs and highest caliber players of its time, paving the way for the origin of the NL in 1876.

Logo for National Association of Base Ball Players
NABBP: 1857-1870 (14 seasons)

The first organization governing professional baseball and establishing standard rules across the national sport.