Boston Red Sox (1908-present)

Boston Americans (1901-1907)

St. Louis Cardinals (1900-present)

St. Louis (1883, 1899)

St. Louis Browns (1882, 1884-1898)

Player must have played for only one major league franchise, or only one AL/NL team, in their career. For example, Tony Gwynn (only played for one team, an AL/NL team), Buck Leonard (only played for one team, a Negro Leagues team), Jackie Robinson (only played for one team in AL/NL, but additionally played for a team in the Negro Leagues), and Mike Griffin (only played with one team in the AL/NL, but additionally played in the AA and PL) would all qualify.