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.
Territories of the United States on stamps
The Panama Canal opening was commemorated on its 25th anniversary with a 3-cent stamp issued on August 15, 1939. The stamp shows a steamship passing through the Gaillard Cut, President Theodore Roosevelt on the left promoted the canal and General George W. Goethals on the right was chief engineer and first governor of the Panama Zone.