According to the National Archives:
• In this transaction with France, the United States purchased 828,000 square miles of land west of the Mississippi River for $15 million.
• That amounts to roughly four cents an acre.
• The lands acquired stretched from the Mississippi River to the Rocky Mountains and from the Gulf of Mexico to the Canadian border. Thirteen states were carved from the Louisiana Territory.
• Robert Livingston and James Monroe signed the Louisiana Purchase Treaty in Paris on April 30, 1803.
• They had been authorized to pay France up to $10 million for the port of New Orleans and the Floridas.
• When offered the entire territory of Louisiana — an area larger than Great Britain, France, Germany, Italy, Spain and Portugal combined — the American negotiators swiftly agreed to a price of $15 million (80 million francs).
• President Thomas Jefferson was a strict interpreter of the Constitution who wondered if the U.S. government was authorized to acquire new territory.
• But Jefferson also was “a visionary who dreamed of an ‘empire for liberty’ that would stretch across the entire continent.”
• Jefferson moved forward with deal the when Napoleon (France’s leader) threatened to take the offer off the table, clearing the way for the westward expansion of the U.S. to “occupy a land of unimaginable riches.”
• The Louisiana Purchase Agreement is made up of the Treaty of Cession and the two conventions regarding the financial aspects of the transaction.
• Details of the two conventions: the first for payment of $11,250,000; the second to settle claims American citizens had made against France for $3,750,000.
Source: The National Archives, citing information excerpted from Stacey Bredhoff, American Originals (Seattle: The University of Washington Press, 2001), p. 26.