Though the present-day United States stretches from the Atlantic Ocean to the Pacific, the shape of the nation has shifted many times over the course of its history. The year 1803 marked one of the greatest changes, when President Thomas Jefferson purchased 828,000 square miles from France's Napoleon Bonaparte. This area of land, known then as the Louisiana Territory, today comprises all or part of 15 states. Buying the territory was no easy task, however. France was wrangling with political and military battles, the deal required the talents of two of Jefferson's most talented diplomats, and even the constitutionality of such land acquisition came under fire.