History of the Panama Canal
During World War II, the canal proved a vital part of the U.S. military strategy, allowing ships to transfer easily between the Atlantic and Pacific. Politically, the Canal remained a territory of the United States until 1977, when the Torrijos–Carter Treaties began the process of transferring territorial control of the Panama Canal Zone to Panama, a process completed on 31 December 1999.
Cristóbal, Colón
In 1904, after Panama's US-backed declaration of independence from Colombia, the Canal Commission set up its provisional headquarters in Cristóbal. By then, the United States had purchased the French Canal enterprise's assets in Panama and had secured use and control of the Canal Zone "in perpetuity." The Panama Railroad's assets also came under Canal Zone control, and its facilities became part of the Canal Zone town of Cristóbal.