SS United States is a retired American ocean liner that was built during 1950 and 1951 for United States Lines. She is the largest ocean liner to be entirely constructed in the United States and the fastest ocean liner to cross the Atlantic Ocean in either direction, earning the Blue Riband for the highest average speed since her maiden voyage in 1952, a title that remains uncontested.
The ship was designed by American naval architect William Francis Gibbs and could have been converted into a troopship if required by the United States Navy in time of war. The ship served as a US icon, transporting celebrities and immigrants throughout her career between 1952 and 1969. Her design included innovations in steam propulsion, hull form, fire safety, and damage control. Despite her record speed, passenger counts declined in the mid-1960s due to the rise in jet-propelled trans-Atlantic flights.
United States was withdrawn from service in a surprise announcement in 1969. All planned cruises were canceled, and the ship changed owners repeatedly for the next several decades. Every owner attempted to make the ship profitable, but she was aging and poorly maintained. In 1984, her interior furnishings were sold at auction, and the rest of her interiors were stripped to the bulkheads in 1994. In 1996, she was towed to Philadelphia, where she remained until February 2025.
Since 2009, the SS United States Conservancy has been raising funds in an attempt to save the ship from being scrapped. The group purchased her in 2011 and has created several unrealized plans to restore the ship. Due to a rent dispute, in 2024, the ship was evicted from her pier. Because no other locations for the ship could be found, Okaloosa County, Florida was able to purchase the ship and plans to sink her by 2026 near Destin to become the world's largest artificial reef.
SS United States was designed by William Gibbs. When Gibbs was eight years old in 1894, he watched the launching of SS St. Louis and became enamored with ships and dreamed of a massive, grand American ship to surpass all others.
As an adult, Gibbs' first project was to lead the redesign and reconstruction of the ocean liner Leviathan, the largest ship in the world and an American war prize following World War I. Once complete, his skill was appreciated by the government, media, and other architects; groups such as the Pacific Marine Review referred to him as "America's foremost naval architect".
The first ship purely of Gibb's design was SS Malolo, a luxury liner for the Pacific Ocean. During her sea trials, the ship was struck amidship by a freighter, ripping a massive hole into Malolo's engine room. The damage was so severe the former Chief of US Navy Construction and Gibb's mentor David Taylor thought the ship would immediately sink, much like RMS Empress of Ireland did in similar circumstances. The ship stayed afloat with little damage and few casualties; this success was credited to Gibb's meticulous designs, further increasing his fame.
Gibbs' work put him in contact with American officials, to whom he pitched his idea for a massive, American-flagged liner. By 1936, the US government was planning to replace the aging Leviathan so a new vessel could operate as a passenger liner during peacetime and as a troop transport during war. Although not the massive ocean liner Gibbs had envisioned, he was selected to design the new ship, which became the SS America.
At the end of the Second World War, Gibbs and his company had designed more than 70% of all American ships used during the conflict, and Gibbs was at the height of his career. He believed it was time to realize his vision of an American superliner.
During World War II, many ocean liners, including Normandie and Queen Mary, were seized or requisitioned by governments and used to transport soldiers between fronts. In 1945, the US Maritime Commission requested designs for a ship that could handle that role for future conflicts. Gibbs submitted a design of his decades-old vision, which eventually won the contract.
The most-promising use of the liner in war would have been as a troop transport. If mobilized, onboard furnishings could easily be removed to make room for a 14,400-man US Army division. The ship's size and speed meant she could rapidly deploy a division anywhere in the world without needing to refuel.
Following the end of World War II, the newly formed US Department of Defense was divided about its policy in the nuclear age. There was controversy around the supercarrier USS United States (CVA-58), which was canceled after her keel was laid. The shipyard, looking for a project to fill the void left by the United States Navy, agreed to dismantle the aircraft carrier and build an ocean liner with, coincidentally, the same name, in the same dry dock, allowing her keel to be laid on February 8, 1950. The circumstance saw United States become the first ocean liner to be built in a dry dock, accelerating her construction because parts of the ship could be prefabricated.
Another major issue facing the Navy was its reduction of transport capabilities following the war. After the Inchon Landings during the Korean War, the Department of Defense realized it lacked troop-transport capacity and requisitioned the one-third-completed United States to quickly and cheaply fill part of the deficit. Under Navy control, stateroom bathrooms were to be stripped and large spaces divided to make room for gun mounts, wardrooms, more lifeboats, and equipment required to support the enlarged passenger count.
United States was requisitioned under Secretary of Defense Louis Johnson, who believed it was cheaper and easier to convert an existing vessel than to build a new one. Days after the announcement was made, the secretary was relieved and replaced by George Marshall. After meeting with the chairman of the Maritime Administration, Marshall believed converting United States would take too long to be of any use during the Korean War. A month after her requisitioning was announced, the Joint Chiefs of Staff reversed the decision and returned the ship to previously scheduled civilian work.
United States was christened and launched on June 23, 1951, sponsored by Lucile Connally, wife of U.S. Senator Tom Connally. Her construction was a joint effort by the United States Navy and United States Lines (USL), and was broken into two parts. The cost of construction was split; USL contributed $25 million and the US government $20 million. The government also paid another $25 million for the incorporation of "national defense features" into her design, which brought her cost to $71.08 million, even though the ship itself cost only $44.4 million.
The ship's power plant was developed in unusual cooperation with the Navy, leading to a militarized design. The ship never used US Navy equipment; the designers opted for civilian variants of military models. The engine room arrangement was similar to that of large warships such as the Forrestal-class aircraft carriers, with isolated engineering spaces, and redundancies and backups in onboard systems.
In normal service, the ship could theoretically generate 310,000 pounds (140,000 kg) of steam per hour, at 925 pounds per square inch (6.38 MPa) and 975 °F (524 °C), using eight US Navy-type M-type boilers; however, they were operated at 54% of their capacity. The boilers were divided among two engine rooms, four in each. Babcock & Wilcox designed the ship's boilers and manufactured those in the forward engine room; the other boilers were made by Foster Wheeler and were located aft.
Steam from the boilers turned four Westinghouse double-reduction geared turbines, each one connected to a drive shaft. Each turbine could generate approximately 60,000 shaft horsepower (45,000 kW), or 240,000 shp (180,000 kW) total. If at flank speed, initial designs estimated 266,800 shp (199,000 kW) from 1,100 °F (593 °C) steam at 1,145 pounds per square inch (7.89 MPa) could be generated.