Louisiana Purchase Treaty

What it is

This is the treaty of cession signed April 30, 1803, by which the United States purchased 828,000 square miles of land west of the Mississippi River from France for $15 million. It is held by the U.S. National Archives.

Why it matters

Negotiators Robert Livingston and James Monroe were originally sent only to buy New Orleans, but France offered the whole Louisiana territory instead. President Jefferson, though he usually read the Constitution strictly and doubted his authority to acquire new land, pushed aside his doubts to seize the opportunity. The purchase doubled the nation's size but ignored its impact on the Native American tribes already living there, and it later deepened tensions over the expansion of slavery into new territories.

Look closer

• Why might Jefferson have set aside his usual strict reading of the Constitution for this treaty?
• What does the treaty not mention that still affected real people living on this land?
• Why was the purchase price so low compared to the size of the territory?