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
The treaty was approved by the provisional Panamanian government on December 2, 1903, and by the US Senate on February 23, 1904. Under the treaty, Panama received , much of which the United States required to be invested in that country, plus annual payments of ; with those payments made, as well as for the purchase of the French company assets, the Canal Zone was formally turned over by Panama on May 4, 1904, when American officials reopened the Panama City offices of the canal company and raised the American flag. This marked the beginning point for U.S. excavation and construction which concluded in August 1914 with the opening of the canal to commercial traffic.