In 1920, Foster called a meeting of Midwestern team owners in Kansas City. There, seven all-black teams formed the first Negro National League, which opened with Foster's Chicago American Giants, the Chicago Giants (different team), the Cuban Stars, the Dayton Marcos, the Indianapolis ABCs, the Kansas City Monarchs and St. Louis Giants [source: NLB]. All except the Monarchs were black-owned [source: The Baseball Page].
The Negro Leagues, for their part, were integrated. They included several Latino teams, primarily Cuban-American, along with a white pitcher, Eddie Klep, who played briefly for the Cleveland Buckeyes in 1946. Klep was barred from taking the field with his black teammates when they played in the South [source: NLB].
After Foster got the ball rolling, other Negro Leagues quickly followed. Teams from Atlanta, Chattanooga, Birmingham, Memphis, Nashville and New Orleans came together in 1920 as the first Negro Southern League, which broke up the same year [source: NLBM]. The Eastern Colored League opened in 1923, and the American Negro League formed in 1928 [sources: NLB, NLB].
Black professional baseball saw success in the '20s. The first Negro League World Series took place in 1924 and continued annually until 1927 [source: BR]. But Foster's Midwestern league alone lasted the whole decade -- and just barely. The League took a hit in the opening years of Great Depression, and in 1931, following the financial collapse of '29 and Foster's death in 1930, the powerful Negro National League went out of business.
Two years later, a Pittsburgh businessman decided to bring it back.