RMS Queen Mary is a retired British ocean liner that sailed primarily on the North Atlantic Ocean from 1936 to 1967 for the Cunard-White Star Line and was built by John Brown & Company in Clydebank, Scotland. Queen Mary, along with RMS Queen Elizabeth, were built as part of Cunard's planned two-ship weekly express service between Southampton, Cherbourg and New York. The two ships were a British response to the express superliners built by German, Italian and French companies in the late 1920s and early 1930s.

Queen Mary sailed on her maiden voyage on 27 May 1936 and won the Blue Riband that August; she lost the title to SS Normandie in 1937 and recaptured it in 1938, holding it until 1952, when it was taken by the new SS United States. With the outbreak of World War II, she was converted into a troopship and ferried Allied soldiers during the conflict.

Following the war, Queen Mary was refitted for passenger service and along with Queen Elizabeth commenced the two-ship transatlantic passenger service for which the two ships were initially built. The two ships dominated the transatlantic passenger transportation market until the dawn of the jet age in the late 1950s. By the mid-1960s, Queen Mary was ageing and was operating at a loss.

After several years of decreased profits for Cunard Line, Queen Mary was officially retired from service in 1967. She left Southampton for the last time on 31 October 1967 and sailed to the port of Long Beach, California, United States, where she was permanently moored. The City of Long Beach bought the ship to serve as a tourist attraction featuring restaurants, a museum and a hotel. The city contracted out management of the ship to various third-party firms over the years. It took back operational control in 2021 when the operator filed for bankruptcy and it was found that extensive repairs were needed to keep the ship from sinking. The ship is listed on the National Register of Historic Places. The National Trust for Historic Preservation has accepted Queen Mary as part of the Historic Hotels of America.

SS United States is a retired ocean liner built in 1950–51 for the United States Lines at a cost of US$79.4 million. The ship is the largest ocean liner constructed entirely in the United States and the fastest ocean liner to cross the Atlantic in either direction, retaining the Blue Riband for the highest average speed since her maiden voyage in 1952. She was designed by American naval architect William Francis Gibbs and could be converted into a troopship if required by the Navy in time of war. United States maintained an uninterrupted schedule of transatlantic passenger service until 1969 and was never used as a troopship.

The ship has been sold several times since the 1970s, with each new owner trying unsuccessfully to make the liner profitable. Eventually, the ship's fittings were sold at auction, and hazardous wastes, including asbestos panels throughout the ship, were removed, leaving her almost completely stripped by 1994. Two years later, she was towed to Pier 82 on the Delaware River, in Philadelphia, where she remains today.

Since 2009, a preservation group called the SS United States Conservancy has been raising funds to save the ship. The group purchased her in 2011 and has drawn up several unrealized plans to restore the ship, one of which included turning the ship into a multi-purpose waterfront complex. In 2015, as its funds dwindled, the group began accepting bids to scrap the ship; however, sufficient donations came in via extended fundraising. Large donations have kept the ship berthed at her Philadelphia dock while the group continues to further investigate restoration plans.