USS Mound City was a City-class ironclad gunboat built for service on the Mississippi River and its tributaries in the American Civil War. Originally commissioned as part of the Union Army's Western Gunboat Flotilla, she remained in that service until October 1862. Then the flotilla was transferred to the Navy and she became part of the Mississippi River Squadron, where she remained until the end of the war.

The Mississippi River Squadron was the Union brown-water naval squadron that operated on the western rivers during the American Civil War. It was initially created as a part of the Union Army, although it was commanded by naval officers, and was then known as the Western Gunboat Flotilla and sometimes as the Mississippi Flotilla. It received its final designation when it was transferred to the Union Navy at the beginning of October 1862.