The United States is unique in getting so much of its territory through peaceful purchases. Among other acquisitions, it bought Louisiana from France in 1803, Florida from Spain in 1845, and Alaska from Russia in 1867.

Even when the expansion was not peaceful, money was often involved. Mexico received dollops of cash for the formal cession of its various conquered territories after 1845: $7.5 million in debt relief for Texas; $15 million for California, New Mexico, and Utah; and, later, $10 million for Arizona. Spain was paid $20 million for the Philippines in 1898.