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
The United States initiated construction in 1850 of the Panama Railroad (now called the Panama Railway) to cross the isthmus and it opened in 1855. This overland link became a vital piece of Western Hemisphere infrastructure, greatly facilitating trade and largely determining the later canal route, which was made parallel to it.