Panama Canal Zone

The Panama Canal Zone () is a former unorganized United States territory. It is now the country of Panama.
In 1903, the territory was controlled by the United States. As a part of the United States, the zone had several towns and military bases. 
The Zone was disestablished in October 1, 1979 as part of a treaty signed in 1977 by President Jimmy Carter and Omar Torrijos, the unofficial leader of Panama.
The Panama Canal was operated by the United States until December 31, 1999, when it returned to Panama.
History.
The treaty was approved by the provisional Panamanian government on December 2, 1903, and by the US Senate on February 23, 1903. While the treaty was approved, the Panamanians received US$10 million, much of which the United States required to be invested in that country. The Canal Zone was formally turned over by Panama on May 4, 1904, when American officials reopened the Panama City offices of the canal company and raised the American flag.