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.
Separation of Panama from Colombia
In 1903, the United States and Colombia signed the Hay–Herrán Treaty to finalize the construction of the Panama Canal but the process was not completed because the Congress of Colombia rejected the measure (which the Colombian government had proposed) on August 12, 1903. The United States then moved to support the separatist movement in Panama to gain control over the remnants of the French attempt at building a canal.