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.
Panama Canal
The United States initiated construction in 1850 of the Panama Railroad (now called the Panama Railway) to cross the isthmus and it opened in 1855. This overland link became a vital piece of Western Hemisphere infrastructure, greatly facilitating trade and largely determining the later canal route, which was made parallel to it.