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.
Panama Canal Zone
In 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 in 1979, as a term of the Torrijos–Carter Treaties two years earlier; the canal itself was later under joint U.S.–Panamanian control until it was fully turned over to Panama in 1999.