The U.S. empire was built on bird dung

 

In a strange but real turn of events, the United States did use bird dung—more especially, guano—to establish a portion of its empire. 

Guano—bird droppings that collect on islands, particularly in the tropics—became a major resource in the 19th century. 

Guano was valued as an effective fertilizer because it was high in potassium, phosphorus, and nitrogen. The Guano Islands Act, which was passed by the United States in 1856 and gave American people the authority to assert U.S. claims to uninhabited islands containing guano resources, was crucial. 

The act successfully expanded U.S. dominance and set the stage for a more expansionist strategy by resulting in the annexation of almost 100 islands, particularly in the Pacific and the Caribbean. 

The invention of synthetic fertilizers diminished the importance of guano, but the Guano Islands Act recognized