
Daniel Immerwahr | How To Hide An Empire, Forgotten History, & Colony Labs
Guano Islands Act and the Foundations of Overseas Expansion
In the 19th century, the United States claimed nearly 100 uninhabited islands to secure guano, which was essential as a nitrate-rich fertilizer for industrial agriculture. This "scramble for guano" was driven by a desire to break British and Peruvian monopolies on the substance. These islands provided the legal framework for the U.S. to extend its jurisdiction and constitutional authority overseas for the first time.

