The Panama Canal Zone (Spanish: Zona del Canal de Panamá) 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 five miles (8.0 km) 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.
On February 26, 1904, the Isthmian Canal Convention was proclaimed. In it, the Republic of Panama granted to the United States in perpetuity the use, occupation, and control of a zone of land and land under water for the construction, maintenance, operation, sanitation, and protection of the canal. From 1903 to 1979 the territory was controlled by the United States, which had purchased the land from the private and public owners, built the canal and financed its construction. The Canal Zone was abolished on October 1, 1979, as a term of the Torrijos–Carter Treaties of 1977; the canal itself was under joint U.S.–Panamanian control from 1979 until it was fully turned over to Panama on December 31, 1999.
The capital was located in Balboa and as of current times, is considered international territory for ships to pass through.