Preparing for my regulation economics class, I decided to use guano as an example. Guano is the bird excrement that piles up on deserted ocean islands. It has a high concentration of urea, and hence of nitrogen in a form crops can use. I wanted to use it as an example of how natural resources should be used up, though used up at an efficient rate. It was heavily mined in the 19th century, and this was appropriate, especially since in 1909 Fritz Haber discovered how to synthesize ammonia cheaply as a substitute. Looking at Wikipedia, I discovered another good feature for an economics class, though: the Guano Islands Act of 1856. 48 USC 1411, 1414 still says:
1411. Whenever any citizen of the United States discovers a deposit of guano on any island, rock, or key, not within the lawful jurisdiction of any other government, and not occupied by the citizens of any other government, and takes peaceable possession thereof, and occupies the same, such island, rock, or key may, at the discretion of the President, be considered as appertaining to the United States….
1414. The discoverer, or his assigns, being citizens of the United States, may be allowed, at the pleasure of Congress, the exclusive right of occupying such island, rocks, or keys, for the purpose of obtaining guano, and of selling and delivering the same to citizens of the United States, to be used therein, and may be allowed to charge and receive for every ton thereof delivered alongside a vessel, in proper tubs, within reach of ship’s tackle, a sum not exceeding $8 per ton for the best quality, or $4 for every ton taken while in its native place of deposit.
Midway and Johnston Atolls, in the general vicinity of Hawaii, were claimed for the U.S. this way.