Guano Islands Act

The Guano Islands Act (11 Stat. 119, enacted 18 August 1856, codified at 48 U.S.C. ch. 8 §§ 1411-1419) is federal legislation passed by the U.S. Congress that enables citizens of the U.S. to take possession of islands containing guano deposits. The islands can be located anywhere, so long as they are not occupied and not within the jurisdiction of other governments. It also empowers the President of the United States to use the military to protect such interests and establishes the criminal jurisdiction of the United States.

Whenever any citizen of the United States discovers a deposit of guano on any island, rock, or key, not within the lawful jurisdiction of any other Government, and not occupied by the citizens of any other Government, and takes peaceable possession thereof, and occupies the same, such island, rock, or key may, at the discretion of the President, be considered as appertaining to the United States.

— first section of Guano Islands Act