USS St. Louis (1861), an ironclad gunboat commissioned in 1862, later renamed Baron de Kalb, and sunk in 1863 during the American Civil War
USS St. Louis, a troop transport in commission in 1898, which otherwise served as the civilian passenger liner SS St. Louis (1894) from 1895 to 1918 and from 1919 to 1920 and was in commission again as the troop transport USS Louisville from 1918 to 1919