The United States became involved in negotiations with France in 1802. President Thomas Jefferson directed Robert Livingston, the U.S. minister to France, to attempt to prevent Spain, which had controlled the strategic port of New Orleans with a relatively free hand since 1762, from ceding it back to France.
Were New Orleans to come under the control of Napoleon Bonaparte, Jefferson feared that American settlers living in the Mississippi valley would lose free access to the port of New Orleans. However, faced with a shortage of cash, a recent military defeat in Santo Domingo, and the threat of a war with Great Britain and the United States over the territory in question, Napoleon decided to cut his losses.
In 1803 he offered to sell the territory to the United States. Livingston and James Monroe, whom Jefferson had sent to Paris with the power to act in his stead, purchased the entire territory.
The bounds of the territory, which were not clearly delineated in the treaty, were assumed to include all the land between the Mississippi River and the Rocky Mountains, at that time known as the Stony Mountains. Just twelve days after the May 2, 1803 signing of the treaty, frontiersmen Meriwether Lewis and William Clark, younger brother of Revolutionary War officer George Rogers Clark, set out on an expedition to explore the newly acquired territory.The purchase of the Louisiana Territory and Lewis and Clark's expedition marked the beginning of a century of conquest. As explorers, speculators, adventurers, and settlers pushed the territorial boundaries of the United States westward toward the Pacific coast, the notion of America as a nation always pushing toward new frontiers took hold in art, literature, folklore, and the national psyce.
Learn more about western expansion in American Memory:
- Search on Louisiana Territory in A Century of Lawmaking, 1774-1875 to read congressional acts and proceedings related to the vast territory.
- See a Map of Lewis and Clark's Track copied by Samuel Lewis from the original drawing of William Clark, or see Lewis and Clark Map with annotations in brown ink by Meriwether Lewis in Map Collections (1500-Present).
- Follow the trail blazed by Lewis and Clark. Visit the National Park Service's Lewis and Clark National Historic Trail Web site or view the timeline for the expedition at PBS's companion site to Ken Burns's film Lewis & Clark: The Journey of the Corps of Discovery.
- Read Henry Rowe Schoolcraft's memoir of his 1832 discovery of the Mississippi River's source, Lake Itasca, Minnesota found in the collection Pioneering the Upper Midwest: Books from Michigan, Minnesota, and Wisconsin, circa 1820-1910.
- Louisiana, Missouri, Arkansas, Iowa, the Dakotas, Nebraska, and Oklahoma, as well as most of Kansas, Colorado, Wyoming, Montana, and Minnesota were carved from the original territory of Louisiana. Search the Today in History Archive on the names of these states to find additional features related U.S. territorial expansion, western exploration and migration. Learn, for example, about the opening of the Erie Canal, the Gadsden Purchase, and the Homestead Act.
- Search the American Memory pictorial collections on these state names to see more images of the territory acquired by the United States in 1803.
- Search the Map Collections (1500-Present) on Louisiana for maps of the territory and state. Find maps of the states, towns, and land features that were originally part of the Louisiana territory by searching on their names.
- Search or browse the subject index of the following collections to find a wealth of photographs, memoirs, and other documents related to the exploration and settlement of the western frontier:
