The United States paid $15 million for the Louisiana Purchase in 1803.
The agreement transferred approximately 828,000 square miles of territory from France to the United States. The price amounted to about three cents per acre, although the final financial burden was higher after interest on the bonds used to pay France.
President Thomas Jefferson authorized the purchase after France offered to sell the entire territory, not merely the port of New Orleans. The treaty was signed on April 30, 1803, and ratified by the U.S. Senate later that year. The acquisition roughly doubled the size of the United States.
The purchase created major opportunities for westward expansion but also intensified disputes over Indigenous sovereignty, slavery, and the political balance between regions. Its enormous geographic consequences make it a major milestone on the road from 1776 to America250.