SS Ideal X, a converted World War II T-2 oil tanker, was the first commercially successful container ship.

Built by The Marinship Corporation during World War II as Potrero Hills, she was later purchased by Malcom McLean's Pan-Atlantic Steamship Company.^[5][6][7] In 1955, the ship was modified to carry shipping containers and rechristened Ideal X. During her first voyage in her new configuration, on 26 April 1956,^[8] the Ideal X carried 58 containers from Port Newark, New Jersey, to Port of Houston, Texas, where 58 trucks were waiting to be loaded with the containers.^[9] It was not the first purpose built container ship: the Clifford J. Rodgers, operated by the White Pass and Yukon Route, had made its debut in 1955.^[10]

In 1959, the vessel was acquired by Bulgarian owners, who rechristened her Elemir. The Elemir suffered extensive damage during heavy weather on 8 February 1964, and was sold in turn to Japanese breakers. She was finally scrapped on 20 October 1964, in Hirao, Japan.

• Cudahy, Brian J. (2006). Box boats: how container ships changed the world. New York: Fordham University Press. ISBN 0-8232-2568-2.
• Cudahy, Brian J. (September–October 2006). "The Containership Revolution: Malcom McLean's 1956 Innovation Goes Global" (PDF). TR News. 246. Washington, D.C.: Transportation Research Board of the National Academies: 5–9. Retrieved 1 March 2011.
• Levinson, Marc (2006). The Box: How the Shipping Container Made the World Smaller and the World Economy Bigger. Princeton, N.J: Princeton University Press. pp. 1. ISBN 0-691-12324-1.

• Vessel data at Dept. of Transportation^{[dead link‍]}
• 26 April 1956: The Container Ship's Maiden Voyage