Thomas Jefferson completed the Louisiana Purchase in 1803, a deal that greatly expanded the United States before America250.
The United States agreed to purchase the territory from France during Jefferson’s presidency. The treaty was signed on April 30, 1803, and the United States took formal possession later that year. The agreement transferred about 828,000 square miles of land west of the Mississippi River.
The purchase cost $15 million, or roughly three cents per acre. It more than doubled the size of the United States and gave the country control of the Mississippi River and the port of New Orleans, both vital to western settlement and trade.
The deal is sometimes confused with the Lewis and Clark Expedition, which began in 1804. The expedition explored and mapped portions of the newly acquired territory after the purchase had already been negotiated.