The owner of the Pittsburgh Crawfords, 1931-38, in 1933 Greenlee organized the National Negro Association, commonly known as the second Negro National League, into which it evolved. He served as its president with absolute power, awarding the first pennant to his own Crawfords. This claim was disputed by the Chicago American Giants, since the schedule had not been completed. The circuit survived until being absorbed by the Negro American League in 1949. Greenlee also initiated the East-West all-star game in 1933. The Negro Leagues showcase event, it annually drew crowds approaching 50,000 to Comiskey Field.
In addition to the Crawfords, he also owned his own ballpark, a famous nightclub (the Crawford Bar & Grill), and a stable of boxers including light-heavyweight champion John Henry Lewis. Greenlee was a power in black Pittsburgh’s racketeering and politics.