Guano Islands Act Information
The Guano Islands Act (11 Stat. 119, enacted August 18, 1856, codified at 48 U.S.C. ch. 8 §§ 1411-1419) is a United States federal law passed by the U.S. Congress that enables citizens of the United States to take possession, in the name of the United States, of unclaimed islands containing guano deposits. The islands can be located anywhere, so long as they are not occupied and not within the jurisdiction of another government. 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 in these territories.
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.— Section 1 of the Guano Islands Act
The Act continues to be part of the law of the United States. The most recent Guano Islands Act claim was made to Navassa Island. However, the claim was discarded because an American court ruled the island was already under American jurisdiction (a claim Haiti disputes). 
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In the 1840s, guano came to be prized as a source of saltpeter for gunpowder as well as an agricultural fertilizer. The United States began importing it in 1843 through New York. By the early 1850s, the U.K. imported over 200,000 tons a year, and U.S. imports totaled about 760,000 tons.  The "guano mania" of the 1850s led to high prices in an oligopolistic market, attempts of price control, fear of resource exhaustion, and eventually the enactment of the Guano Islands Act 1856 in August 1856.  The Act enables U.S. citizens to take possession of unclaimed islands containing guano for the U.S., and empowering the President to send in armed military to intervene. This encouraged American entrepreneurs to search and exploit new deposits on tiny islands and reefs in the Caribbean and in the Pacific.
This is the beginning of the concept of insular areas in U.S. territories. Up to this time, any territory acquired by the U.S. was considered to have become an integral part of the country unless changed by treaty and eventually to have the opportunity to become a state of the Union. With insular areas, land could be held by the federal government without the prospect of its ever becoming a state in the Union.
Section 6 provides that criminal acts on or adjacent to these territories "shall be deemed committed on the high seas, on board a merchant ship or vessel belonging to the United States; and shall be punished according to the laws of the United States relating to such ships or vessels and offenses on the high seas ..."  The provision was considered and ruled constitutional by the U.S. Supreme Court in Jones v. United States, 137 U.S. 202 (1890).
More than 100 islands have been claimed for the United States under the Guano Islands Act, but most claims have been withdrawn. The Act specifically allows the islands to be considered possessions of the U.S., but it also provides that the U.S. is not obliged to retain possession after guano is exhausted. On the other hand, it also does not say that the U.S. cannot retain possession though the guano is exhausted.
The Act does not specify what the status of the territory is after it is abandoned by private U.S. interests.
The islands still claimed by the United States under the Act are:
- Baker Island 
- Howland Island 
- Jarvis Island 
- Johnston Atoll 
- Kingman Reef/ Danger Rock 
- Midway Atoll 
- Navassa Island  (claimed by Haiti)
- Bajo Nuevo Bank  (disputed with Colombia)
- Serranilla Bank  (disputed with Colombia)
- Swains Island (part of American Samoa; no evidence that guano was mined) 
The claim by the United States under the Guano Act of 1856 to a number of islands are subject to territorial disputes. In most cases, the dispute stems from attempts by a state to expand its exclusive economic zone over the surrounding seas.
To cement the U.S. claim to Navassa Island against Haiti, President James Buchanan issued Executive Orders establishing United States territorial jurisdiction beyond just the Guano Act of 1856. The United States Supreme Court in 1890 ruled the Guano Act constitutional; and, citing the actions of the Executive Branch, amongst other points in law, determined Navassa Island as pertaining to the United States.  Control of Navassa Island was transferred by the Department of the Interior to the Director of the Office of Insular Affairs under Order No. 3205 on January 16, 1997. Both the Department of the Interior and Insular Affairs would later grant administration responsibilities to the United States Fish and Wildlife Service under Order No. 3210 on December 3, 1999. Order No 3210 also established a 12-nautical-mile (22 km; 14 mi) territorial sea boundary for the United States around Navassa Island.
In 1964, Leicester Hemingway, brother of author Ernest Hemingway, attempted to establish a country (or more appropriately, a micronation) dubbed the Republic of New Atlantis, on an 8 x 30 foot bamboo raft anchored with an engine block outside the territorial waters of Jamaica, using the Guano Islands Act as part of a claim to sovereignty. His apparent intention was to use the new country as the headquarters for his own International Marine Research Society, with which he planned to further marine research, as well as to protect Jamaican fishing. Neither the US nor Jamaica recognized his claim before the raft was destroyed in a storm in 1966.  
- List of Guano Island claims
- United States Miscellaneous Pacific Islands
- United States Minor Outlying Islands
- Underhill, Kevin (July 8, 2014). "[By Kevin Underhill:] The Guano Islands Act" – via www.washingtonpost.com.
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several islands first claimed under the guano island law; Kindle location 2856 of 15675.
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- "Guano is Back…". McGill University, March 20, 2017.
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