The ship that became famous as the Ideal X began life as a mass-produced T-2 tanker called the Potrero Hills, launched on December 30, 1944 by the Marinship Corporation of Sausalito, California. It changed ownership and names several times after the conclusion of World War II, but in 1955 was acquired by the Pan-Atlantic Steamship Company of Mobile, Alabama. The Pan-Atlantic Steamship Company had been a subsidiary of the Waterman Steamship Company, but was acquired by a North Carolina trucking executive named Malcolm McLean. McLean had long complained about the antiquated process of breakbulk shipping. He thought that shipping virtually the entire truck as a package rather than its individual contents separately would make the process more efficient. He installed above the main deck of the Ideal X a special spar deck with longitudinal slots to which he attached the bodies of 58 tractor trailers. The Ideal X departed from Berth 24 in Port Newark, New Jersey on April 26, 1956. It arrived in Houston, Texas on May 2. The vessel’s below-deck cargo tanks were empty, but the carriage of the 58 tractor trailer bodies above deck was precedent-setting. The trailer bodies were promptly unloaded, attached to running gear, and hauled away by 58 semi-trucks working for Mr. McLean. In 1957, the Pan-Atlantic Steamship Company acquired and converted the SS Gateway City, which it modified to carry containers stacked on top of each other below decks, with more carried as deck cargo. The 524-foot long Ideal X could carry 58 trailers, while the 450-foot long Gateway City had a capacity of 226 containers. In 1960, the company was renamed Sea-Land Service (now known as Horizon Lines). By that time, the Ideal X had been sold to a foreign company and renamed the Elemir. Several years later, it suffered extensive damage in heavy weather. It was scrapped in Japan in 1964, but not before it had radically changed the shipping industry.