How many square miles did the United States acquire in the Louisiana Purchase?

The United States acquired approximately 828,000 square miles in the Louisiana Purchase.

In 1803, the United States agreed to pay France $15 million for the Louisiana Territory. The transaction more than doubled the country’s land area and gave the United States control or a claim across much of the Mississippi River drainage basin west of the river.

The purchase was negotiated during Thomas Jefferson’s presidency. Napoleon Bonaparte decided to sell partly because France had failed to reestablish control in Saint-Domingue and faced the prospect of renewed war with Britain. The United States, meanwhile, wanted secure access to the Mississippi River and the port of New Orleans.

The boundaries and practical meaning of the purchase were not immediately simple. France’s control over much of the territory was limited, and Indigenous nations already lived throughout the region. Later treaties clarified borders with Spain and Britain, while exploration and settlement extended U.S. claims across the continent.