SS Antigua was a United Fruit Company passenger and refrigerated cargo liner completed as one of six nearly identical vessels, three built by Newport News Shipbuilding and three by Bethlehem Shipbuilding Corporation, for operation by the company's subsidiary the United Mail Steamship Company. The ship was the first of the ships built by Bethlehem Shipbuilding Corporation, Quincy, Massachusetts.
The company's primary business was the banana trade, but some passenger service had been a part of its business. Requirements of the United States implemented to obtain subsidies and mail contracts drove a design for a larger ship to transport the same amount of fruit. The resulting design was for a ship with more passenger space and features of ocean liners not before incorporated into the company's ships. The ships were designed to carry up to 113 passengers, all first class, with public spaces including a swimming pool, a ballroom and other features of passenger liners. Special mail transport features were in the design and included special space for valuables. The company designated the six ships as its "Mail class" ships. Three ships were assigned routes from New York to Cristóbal, Colón, Panama and three, including Antigua, to its San Francisco to Balboa, Panama route. An intercoastal connection was thus maintained for the line's passengers and freight.
By 1936 the line transferred its ships to the Atlantic and with U.S. entry into the war the ships were all placed under bareboat charter to the War Shipping Administration (WSA) for the duration. Antigua was the only ship of the six not then placed under sub bareboat charter to the Navy to be commissioned and serving as a Navy ship with naval crew. After the war the ship was returned to the company and served on a similar route as before the war.