SS Ohio was an iron passenger-cargo steamship built by William Cramp & Sons in 1872. The second of a series of four Pennsylvania-class vessels, Ohio and her three sister ships—Pennsylvania, Indiana and Illinois—were the largest iron ships ever built in the United States at the time of their construction, and amongst the first to be fitted with compound steam engines. They were also the first ships to challenge British dominance of the transatlantic trade since the American Civil War.