Plymouth's keel was laid down in 1915 by the New York Shipbuilding Company of Camden, New Jersey, was taken over from the Italian-American Steamship Company by the United States Shipping Board (USSB) and simultaneously transferred to the United States Navy on 30 July 1918 and commissioned at New York Navy Yard on 2 August.

Assigned to the Naval Overseas Transport Service (NOTS), Plymouth loaded military supplies at Baltimore, Maryland; sailed for Hampton Roads on 21 August 1918 to join a convoy bound for France; and arrived Brest on 11 September.

Upon returning to New York City from La Pallice on 17 October, the ship again sailed for France with a United States Army cargo, arriving at St. Nazaire on 9 December 1918.

Plymouth returned to Philadelphia, Pennsylvania, on 10 January 1919 and steamed on to New York City.

She decommissioned there on 25 February and transferred to USSB for disposal.