United States map showing the area included in the Louisiana Purchase.

October 20, 1803

The U.S. Senate approves the Louisiana Purchase that adds more than 800,000 acres of land – including what would become Missouri – to more than double the size of the United States.


Old postage stamp that commemorates the signing of the Louisiana Purchase.

October 20, 1803

This date in Missouri history. The U.S. Senate approves the Louisiana Purchase that adds more than 800,000 acres of land – including what would become Missouri – to more than double the size of the United States.