The French territory called Louisiana, extending from New Orleans up the Missouri River to modern-day Montana, was intended as a granary for this empire and produced flour, salt, lumber, and food for the sugar islands. By the terms of the 1763 Treaty of Fontainbleau, however, Louisiana west of the Mississippi River was ceded to Spain, while the victorious British received the eastern portion of the huge colony.

When the United States won its independence from Great Britain in 1783, one of its major concerns was having a European power on its western boundary, and the need for unrestricted access to the Mississippi River. As American settlers pushed west, they found that the Appalachian Mountains provided a barrier to shipping goods eastward. The easiest way to ship produce was to build a flatboat and float down the Ohio and Mississippi Rivers to the port of New Orleans, from which goods could be put on ocean-going vessels. The problem with this route was that the Spanish owned both sides of the Mississippi below Natchez.

In 1795 the United States negotiated the Pinckney Treaty with Spain, which provided the right of navigation on the river and the right of deposit of U.S. goods at the port of New Orleans. The treaty was to remain in effect for three years, with the possibility of renewal. By 1802, U.S. farmers, businessmen, trappers and lumbermen were bringing over $1 million worth of produce through New Orleans each year. Spanish officials were becoming concerned, as U.S. settlement moved closer to their territory. Spain was eager to divest itself of Louisiana, which was a drain on its financial resources. On October 1, 1800, Napoleon Bonaparte, First Consul of France, concluded the Treaty of San Ildefonso with Spain, which returned Louisiana to French ownership in exchange for a Spanish kingdom in Italy.

Napoleon's ambitions in Louisiana involved the creation of a new empire centered on the Caribbean sugar trade. By terms of the Treaty of Ameins of 1800, Great Britain returned ownership of the islands of Martinique and Guadaloupe to the French. Napoleon looked upon Louisiana as a depot for these sugar islands, and as a buffer to U.S. settlement. In October of 1801 he sent a large military force to retake the important island of Santo Domingo, lost in a slave revolt in the 1790s.

Thomas Jefferson, the third President of the United States, was disturbed by Napoleon's plans to re-establish French colonies in America. With the possession of New Orleans, Napoleon could close the Mississippi River to U.S. commerce at any time.