On this day (July 4) in 1803, the terms of the treaty between the United States and France for the purchase and sale of Louisiana — the Vente de la Louisiane or “Louisiana Purchase“, a treaty that quite possibly changed the course of world history — are announced to the public: $15 million for 828,000 square miles west of the Mississippi River.

Reblogged this on prior probability and commented:
On this day (20 October) in 1803, the United States Senate ratified the Louisiana Purchase treaty by a vote of 24 to 7. More details here, via Wikipedia.