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.
Ancón, Panama
During the years when the Panama Canal was under the control of the United States, many administrative facilities, military bases, and communities were built in the adjacent areas, forming part of the former Panama Canal Zone. When these areas were reverted to Panama under the Torrijos-Carter Treaties, several alternatives were proposed to integrate the district to the city of Panama. The current district of Ancón was created when a new political-administrative division for the reverted areas was adopted, by Act No. 18 of August 29, 1979, and later amended by Law No. 1 of October 27, 1982. The areas located in the Pacific sector became part of this district, while those located on the Atlantic side were incorporated into the district of Cristobal, in the province of Colon. They remain characterized by a strong US urban architectural style.