Panama Canal Zone
The Panama Canal Zone () was an unincorporated territory of the United States from 1903 to 1979, centered on the Panama Canal and surrounded by the Republic of Panama. The zone consisted of the canal and an area generally extending on each side of the centerline, excluding Panama City and Colón, which otherwise would have been partly within the limits of the Zone. Its border spanned three of Panama's provinces. When reservoirs were created to assure a steady supply of water for the locks, those lakes were included within the Zone.
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.