On 30th April 1803, the Louisiana Purchase Treaty was concluded. France agreed to sell 828,000 square miles of territory that stretched from the Mississippi River to the Rocky Mountains, and which doubled the size of the United States. Although the land transfer went on to include a vast area that now forms part of fifteen separate states, America’s original interest was just in buying the port of New Orleans.
New Orleans offered important access to both the Mississippi River and the Gulf of Mexico, so was vital to American trade and the provision of supplies to the new Western territories that were being settled at the time. When France regained control of the city from Spain in the early 1800s, it raised fears that access would be restricted.
These fears were realized when, on October 18th 1802, Americans were banned from using warehouses in New Orleans. President Jefferson had already ordered diplomats to begin talks in Paris with the aim of buying the city from France. However, on 11th April 1803, the French negotiators offered to sell the entire Louisiana Territory to the Americans for $15 million. Facing an impending war with Britain, and having failed to suppress an uprising in present-day Haiti by slaves and free blacks, France simply couldn’t afford to send troops to occupy and control the Mississippi valley. Deciding to cut their losses, the French government therefore agreed to sell the entire territory at less than 3 cents per acre.