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.
Palmyra Atoll
With imminent opening of the Panama Canal, Palmyra became strategically important. Britain had established a submarine cable station for the All Red Line on nearby Fanning Island. So the U.S. Navy sent to Palmyra, where on February 21, 1912, American sovereignty was formally reaffirmed.