In 1920 baseball banned the spitball pitch to all but 17 existing active spitballers who threw it. Among the 17 was Red Faber who like the others on the list, was able to legally throw the spitball util he retired.
Faber threw the pitch until 1933 when he played his last game with the Chicago White Sox. Interestingly, at the time of his retirement, Faber was the last American League spitballer. However, after lifetime NL hurler Burleigh Grimes was released by the Cardinals in May, 1938, the Yankees signed the spitball-throwing Grimes to make him the final man on the Junior Circuit to legally throw the pitch.
After 10 appearances for New York, Grimes was released and soon signed with the Pittsburgh Pirates for whom he’d finish the season before retiring.