Guano: Oil of the 1800s

Guano, though no saint, works many miracles
-- Peruvian proverb

One of the stranger U.S. laws on the books is Guano Islands Act of 1858. Guano (dried bird poop) became a much-prized commodity to farmers around the world in the 1840s due to the efforts of some clever businessmen from Peru, Britain and France. Guano, a natural fertilizer, greatly increased the crop yield of farmland.

Guano accumulates in deposits hundreds of feet thick on oceanic islands with little rainfall and large fisheries nearby. Fairly easy to "mine" and ship, with the added bonus of being nearly odorless, the huge income its export generated for Peru and her trading partners drove explorer/entrepreneurs on a mad search of the oceans to find their own guano islands. Budding American guano merchants like W.R. Grace and Alfred G. Benson enlisted the aid of Congress, the act allowed the U.S. Navy to defend any guano islands discovered claimed by Americans.

The guano trade was quite profitable until the early 20th century, when the invention of chemical fertilizers largely killed the demand for this dwindling commodity. Or did the dwindling supply of guano (the mining process tended to kill off the birds that produced it) fuel the development of chemical fertilizers?

Some historians feel the Guano Islands Act played a part in turning America into an international economic and military actor after the conclusion of the Civil War.

A few of the more famous islands claimed by America during this time were Midway and Howland.