Beginning in 1937, the Negro National League, which had been the sole Negro League since 1933, concentrated on franchises located in the East, and the Negro American League was organized under leadership by Dr. J.B. Martin to focus on franchises located in the Midwest.
From 1942-1948, the two leagues agreed to play in a Negro League World Series, resuming a championship event that had not taken place in Negro League Baseball since the demise of the ECL ended the Colored World Series in 1927.
After the signing of Jackie Robinson in 1947 into the MLB, the integration of baseball signaled and end to Negro League Baseball. The Negro American League resorted to barnstorming an minor league status sometime between 1950-1951.
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