Because in 1857, not long after the Gadsden Purchase was ratified (1854), the United States began annexing small islands throughout the Caribbean and the Pacific. By the end of the century, it would claim almost a hundred of them. The islands had no indigenous populations and, at the time, no strategic value. They tended to be remote, rocky, and rainless—poor places to grow things on. But that didn’t matter. They had the one thing that everyone in the nineteenth century badly wanted. They had “white gold,” known in less polite circles as bird shit.
