United States territorial acquisitions
The Panama Canal Zone was an unorganized US territory located within the Republic of Panama. It was established under the Hay–Bunau-Varilla Treaty in 1903 and disestablished in 1979 under the Torrijos–Carter Treaties. Panama gained full control over the Panama Canal in 1999.
History of Panama (1821–1903)
Naval operations during the Spanish–American War (1898–1901) served to convince U.S. President Theodore Roosevelt that the United States needed to control a canal somewhere in the Western Hemisphere. This interest culminated in the Spooner Bill of June 29, 1902, providing for a canal through the isthmus of Panama, and the Hay–Herrán Treaty of January 22, 1903, under which Colombia gave consent to such a project in the form of a 100-year lease on an area 10 kilometers wide. This treaty, however, was not ratified in Bogotá, and the United States, determined to construct a canal across the isthmus, intensively encouraged the Panamanian separatist movement.