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)
Nevertheless, Colombia continued to express interest in negotiating with the United States on building a canal. A treaty was signed in 1846 between the two countries. The treaty removed the existing restrictive tariffs and gave the United States and its citizens the right of free transit of persons and goods over any road or canal that might be constructed in the isthmus. In addition, the United States guaranteed the neutrality of the isthmus and Colombia's sovereignty over it, with a view to ensuring uninterrupted transit for the duration of the treaty, which was to be twenty years or as long thereafter as the parties gave no notice to revise it. Called the Mallarino–Bidlack Treaty of 1846, it was actually ratified and became effective in 1848.