Panama Canal Zone
The Panama Canal Zone () was an unincorporated territory of the United States from 1903 to 1979, centered on the Panama Canal and surrounded by the Republic of Panama. The zone consisted of the canal and an area generally extending on each side of the centerline, excluding Panama City and Colón, which otherwise would have been partly within the limits of the Zone. Its border spanned three of Panama's provinces. When reservoirs were created to assure a steady supply of water for the locks, those lakes were included within the Zone.
History of Panama (1977–present)
The second treaty, the Treaty Concerning the Permanent Neutrality and Operation of the Panama Canal, or simply the Neutrality Treaty, was a much shorter document. Because it had no fixed termination date, this treaty was the major source of controversy. Under its provisions, the United States and Panama agreed to guarantee the canal's neutrality "in order that both in time of peace and in time of war it shall remain secure and open to peaceful transit by the vessels of all nations on terms of entire equality". In times of war, however, United States and Panamanian warships were entitled to "expeditious" transit of the canal under the provisions of Article VI. A Protocol was attached to the Neutrality Treaty, and all nations of the world were invited to subscribe to its provisions.