 After the United States joined the Allies , Yorktown operated off the coast of Mexico until August 1917 , when she paused briefly at San Diego . On 18 July 1917 , Yorktown rescued the last surviving members of an abandoned guano mining settlement on Clipperton Island . From a peak population of roughly 100 in 1915 , only four women and seven children survived . After her time off the Mexican coast , Yorktown then cruised off the west coasts of Central and South America into 1918 . After a refit at Mare Island , Yorktown , sailed for the east coast on 28 April 1918 , transiting the Panama Canal en route , and arrived at New York on 20 August . The gunboat escorted a coastal convoy to Halifax , soon there after before returning to New York . She performed local coastwise escort duties through the end of World War I. After a period of upkeep at the New York Navy Yard in December , she departed the east coast on 2 January 1919 on her last voyage to California . 
