As sports progressed, race relations progressed at a comparable rate. In baseball for instance, African Americans were barred from participation in the National Association of Baseball Players because of regional prejudice and unofficial color bans dating back to the 1890s. Due to this segregation, blacks worked together to create the Negro leagues. These leagues comprised mostly all African-American teams. As a whole, the Negro leagues became one of the largest and most successful enterprises run mainly by African Americans. Their founding and resilient growth stood as a testament to the determination and drive of African-Americans to battle the imposing racial segregation and social disadvantage.