USS R-1 (SS-78) was the lead ship of the R-class coastal and harbor defense submarines of the United States Navy. Her keel was laid down on 16 October 1917 by the Fore River Shipbuilding Company in Quincy, Massachusetts. She was launched on 24 August 1918 sponsored by Mrs. George W. Dashiell, and commissioned on 16 December 1918 at Boston, Massachusetts, with Commander Conant Taylor in command.