Louisiana Purchase

The Louisiana Purchase was the acquisition by the United States of the vast territory of Louisiana from the French Republic in 1803. For $15 million the United States gained a claim to roughly 828,000 square miles west of the Mississippi River, nearly doubling the country's nominal size. France, however, controlled only a small part of the land, most of which was home to Native American nations who were not consulted.

France had claimed Louisiana since 1682 but ceded it to Spain in 1762, near the end of the Seven Years' War. For the young United States, the key issue was the Mississippi and the port of New Orleans, through which farmers west of the Appalachians shipped their produce. Under a 1795 treaty, Spain allowed Americans to store goods there for export, but it withdrew that right in 1798, though it was later restored.

In 1800 Napoleon, then First Consul, secretly obtained Louisiana back from Spain as part of a plan to rebuild a French empire in America. The news alarmed President Thomas Jefferson, who feared French troops on the Mississippi, and he sent Robert Livingston and later James Monroe to Paris to try to buy New Orleans.

Napoleon's American plans depended on retaking Saint-Domingue, where formerly enslaved people under Toussaint Louverture had taken control during the Haitian Revolution. The French expedition sent there in 1801 captured Louverture but was ravaged by resistance and disease. By early 1803, with a new war against Britain approaching, Napoleon decided that Louisiana was of little use to him and might easily be lost.

On 11 April 1803 his treasury minister, François Barbé-Marbois, offered the Americans the whole of Louisiana. Although they had been authorised only to buy New Orleans and its surroundings, Livingston and Monroe accepted, and the treaty was signed in Paris on 30 April 1803.

Jefferson, who believed in a strict reading of the Constitution, at first thought an amendment might be needed to acquire new territory, but was persuaded that the treaty-making power was enough. Federalists, especially in New England, opposed the purchase over its cost and the political weight it would give to new western states. The Senate approved the treaty by 24 votes to 7 on 20 October 1803. The money was raised largely through bonds handled by Barings of London and Hope & Co. of Amsterdam.

Spain formally handed Louisiana to France at New Orleans on 30 November 1803, and France transferred it to the United States there on 20 December. Upper Louisiana changed hands at St. Louis in March 1804. The treaty did not define the borders, and disputes followed; the boundary with Spanish territory was settled by the Adams–Onís Treaty of 1819, and the northern line with British North America by a convention of 1818. The land now forms all or part of fifteen US states and two Canadian provinces.

The purchase gave the United States control of the Mississippi and opened the way to westward expansion, beginning with the Lewis and Clark expedition. The territory's settler population included many enslaved people, and the question of whether slavery should spread to new states created from the land became a bitter dispute, addressed for a time by the Missouri Compromise of 1820. For Native Americans, the following decades saw many nations removed from their lands east of the Mississippi to the newly acquired West, most notoriously on the Trail of Tears.

Our 1800 map shows Spanish Louisiana beside the United States shortly before the sale, and our 1815 map shows the territory as part of the United States.