On 14 August 1918 the Emergency Fleet Corporation (EFC) signed a contract with the Northwest Steel Co. to build ten vessels of approximately 8,800 deadweight.

After realizing that there was no need for so many cargo vessels, but rather there existed a shortage of tankers, EFC rescinded its contractual obligations on six of the remaining ships on 15 September 1919.

[2] Swiftstar was the third of these vessels and was laid down at the builder's shipyard in Portland (yard number 42) and launched on 5 February 1921, with Mrs. Nelson Bowles of Seattle serving as the sponsor.

[3][4][1] The ship was shelter-deck type, had two main decks and was built on the Isherwood principle of longitudinal framing providing extra strength to the body of the vessel.

[10] The tanker was initially employed in carrying oil from Mexican ports of Tampico, Túxpan, Puerto Lobos and Tecomate to New York, however, in late spring 1921 a fight erupted between the owners of United States Mail Steamship Company headed by Charles and Francis R. Mayer and the USSB.

[13] Swiftstar passed through Panama Canal on her first trip on new route on 3 September 1922 bound for San Pedro,[14] and after taking on 10,132 tons (~70,000 barrels) of oil from the terminals of the Union Oil Company, departed for her return journey on 19 September 1922 under command of captain Kenney, who was replacing her usual commander, captain James P.

By 11:00 the after-peak bulkhead finally gave in and the engine room got flooded very rapidly cutting off the dynamo and severing any means of communications.

[17][18][19][20] After four days of work the vessel was finally dislodged from her position in the morning of October 15 by wrecking tug Resolute and towed to New London for temporary repairs.

The ship was then towed to the yard of Newport News Shipbuilding & Drydock Company in mid-November 1922, where repairs at a cost of US$171,500.00 were performed.

In June 1923 while en route from Providence to San Pedro, one of the sailors was arrested on board the tanker and put in chains after a wireless message was received identifying him as a suspect in murder and robbery committed in Rhode Island.

[25] Swiftstar cleared for her last voyage from San Pedro with a cargo of 11,400 tons of crude oil (~79,000 barrels) on 30 June 1923 bound for Fall River.

As the schooner closed in to investigate, the crew discovered a large number of splinters floating everywhere in the oil-covered sea, in addition to two wooden and one steel rudderless lifeboats.

Apparently, he had been detained in Panama after attempting to smuggle a bottle of liquor into Canal Zone and as a result missed his ship and avoided the fate of the rest of the crew.