The reason the U.S. took possession of so many small islands in the Pacific and Oceania was due to an 1856 Act passed by Congress amid that first rush to seize the nitrate-rich bird droppings found on those Peruvian rocks. It was thanks to the Guano Islands Act, which allowed U.S. citizens to occupy any unclaimed, uninhabited island containing bird droppings, that the U.S. took possession of Midway Atoll, Howland Island and a host of other barren, desolate rocks in the middle of nowhere.
