Jefferson approved and ordered the Louisiana Purchase with Napoleon Bonaparte, the Emperor of France. Jefferson desired to acquire the French colony of Louisiana mainly to acquire the port city of New Orleans for commerce and defense purposes. James Monroe and Robert R. Livingston negotiated the purchase with French authorities. The $15 million purchase included more than 800,000 square miles, and roughly doubled the size of the United States. Congress approved the purchase—completed in the form of a treaty—by a vote of twenty-four to seven.

Upon the agreement, Livingston said: “From this day the United States take their place among the powers of the first rank.”