The United States Maritime Commission was an independent executive agency of the U.S. federal government that was created by the Merchant Marine Act of 1936, which was passed by Congress on June 29, 1936, and was abolished on May 24, 1950. The commission replaced the United States Shipping Board which had existed since World War I. It was intended to formulate a merchant shipbuilding program to design and build five hundred modern merchant cargo ships to replace the World War I vintage vessels that comprised the bulk of the United States Merchant Marine, and to administer a subsidy system authorized by the Act to offset the cost differential between building in the U.S. and operating ships under the American flag. It also formed the United States Maritime Service for the training of seagoing ship's officers to man the new fleet.
As a symbol of the rebirth of the U.S. Merchant Marine and Merchant Shipbuilding under the Merchant Marine Act, the first vessel contracted for was SS America. Owned by the United States Lines, she briefly operated in the passenger liner and cruise service before being converted into a high-speed transport, per her design.
From 1939 through the end of World War II, the Maritime Commission funded and administered the largest and most successful merchant shipbuilding effort in world history. By the end of the war, U.S. shipyards working under Maritime Commission contracts had built a total of 5,777 oceangoing merchant and naval ships and many smaller vessels.
A huge postwar contraction followed, with massive sell-offs to foreign militaries and commercial fleets. The last major shipbuilding project undertaken by the Commission was to oversee the design and construction of the super passenger liner SS United States which was intended to be both a symbol of American technological might and maritime predominance but also could be quickly converted into the world's fastest naval troop transport.
The Maritime Commission was abolished on 24 May 1950, and its functions were divided between the U.S. Federal Maritime Commission which was responsible for regulating shipping trades and trade routes and the United States Maritime Administration, which was responsible for administering the construction and operating subsidy programs, maintaining NDRF, and operating the U.S. Merchant Marine Academy which had been built and opened during World War II and which continues to be funded as the nation's federally operated maritime academy under 46 USC 310.