Louisiana Purchase
President Jefferson completed the Louisiana Purchase, doubling the size of the United States by acquiring 828,000 square miles from France for approximately $15 million.
What Happened
Napoleon Bonaparte, needing funds for his European wars and facing the loss of Haiti after a slave revolt, offered to sell the entire Louisiana Territory to the United States. Jefferson, who had authorized negotiations only to purchase New Orleans and Florida, jumped at the offer despite concerns about its constitutionality. Congress ratified the treaty in October 1803. The purchase doubled U.S. territory at roughly 3 cents per acre, adding land that would eventually become all or part of 15 states.
Why It Mattered Then
The Louisiana Purchase secured American control of the Mississippi River and New Orleans — vital to western commerce — and opened a vast interior for expansion. It also established the precedent of presidential action on constitutional questions where the text was silent.
Why It Matters Now
The Louisiana Purchase transformed the United States from a coastal republic into a continental nation. It set the trajectory for westward expansion and eventually for the conflicts over slavery in the new territories that would lead to the Civil War.
Key Themes
This event is part of the 1790s–1820s: The Early Republic era (1790s–1820s).
Explore This Era →