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)
The Republic of Panama became a de facto protectorate of the larger country through two provisions whereby the United States guaranteed the independence of Panama and received in return the right to intervene in Panama's domestic affairs. For the rights it obtained, the United States was to pay the sum of US$10 million and an annuity, beginning 9 years after ratification, of US$250,000 in gold coin. The United States also purchased the rights and properties of the French canal company for US $40 million.