USS Keystone State was a wooden sidewheel steamer that served in the Union Navy during the American Civil War. Keystone State was built at Philadelphia, Pennsylvania in 1853 by J. W. Lynn. She was chartered by the navy on 19 April 1861 from the Ocean Steam Navigation Co. at Philadelphia, and purchased on 10 June 1861. She commissioned at Philadelphia Navy Yard on 19 July 1861, Commander G. H. Scott in command.