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.
History of Panama
On September 7, 1977, the Torrijos–Carter Treaties were signed by the Panamanian head of state Omar Torrijos and US President Jimmy Carter for the complete transfer of the Canal and the 14 US army bases from the US to Panama by 1999. These treaties also granted the US a perpetual right of military intervention. Certain portions of the Zone and increasing responsibility over the Canal were turned over in the intervening years.