The SS United States was an American ocean liner built for United States Lines and designed by naval architect William Francis Gibbs. Launched in 1952, it was the largest passenger ship ever built in the United States. Its construction was a joint venture between the government and the shipping company, with the ship also designed to be quickly converted into a troop transport or hospital ship if needed. For this reason, its design included features like fireproof materials, extensive use of lightweight aluminum, and a powerful propulsion system.

On its maiden voyage in 1952, the SS United States set a new speed record for the fastest transatlantic crossing by a passenger liner in both directions, a record that remains uncontested. It won the prestigious Blue Riband for this achievement. The ship was known for its modern and fire-safe interiors and its ability to carry nearly 2,000 passengers.

The SS United States's service career was relatively short, lasting from 1952 until 1969. The rise of commercial jet travel in the 1960s made transatlantic voyages by sea less popular and less profitable. After being withdrawn from service, the ship was laid up and passed through a number of owners over the decades, with several attempts at restoration or repurposing failing to materialize. Much of its interior was stripped and sold off.

As of late 2025, the ship's final chapter is underway. It has been acquired by Okaloosa County, Florida, with the intention of sinking it to create the world's largest artificial reef.