In 1803, the Louisiana Purchase doubled the size of the United States, and brought with it new cultures, new citizens, and vast natural resources. For many Americans, the lands of the Louisiana Purchase became "the West" of dream and legend, representing personal opportunity and national destiny. For many others, such as the Osage and Fox peoples, as well as the French and Spanish residents, the Purchase brought mixed feelings about how American government and culture might affect their traditions and lands.

The region that became the state of Missouri was then part of Upper Louisiana. The scattered communities of European settlers were mostly French, reflecting France's influence in the region since the early eighteenth century. In 1762, France ceded the region to Spain, but the change in government had little effect on the daily lives of Louisiana Territory residents. When France regained the Louisiana Territory in 1800, Spanish officials (many of them French) continued to govern the territory. The transfer wasn't even announced to America until 1802.

President Thomas Jefferson was, by that time, already planning a trade and exploration expedition through the western regions of the continent to the Pacific-a mission into foreign territory. American trade interests became even more pressing when the Spanish closed the port of New Orleans to American traffic coming down the Mississippi. Gaining control of the Mississippi and, if possible, lands west of the river became a serious concern.

Jefferson hoped to expand the nation's trade connections and acquire more land for the fast-growing American population. Although he doubted whether the Constitution gave him the authority to create, in essence, an American empire, Jefferson gave diplomats orders to negotiate for the purchase of New Orleans. The French were not, at first, receptive. However, Napoleon's loss of control over Haiti-his only real stronghold in the Americas-and his need for funds to fight Britain in Europe made the sale of France's American holdings more attractive. American negotiators Robert Livingston and James Monroe took a chance, overstepped their orders, and accepted the offer of the entire Louisiana Territory for approximately $15,000,000-about two cents an acre. They signed the treaty on April 30, 1803.

Lower Louisiana was transferred to the United States at New Orleans in December of 1803. On March 9-10, 1804, the United States took possession of Upper Louisiana at St. Louis (on a spot now part of the Gateway Arch grounds). The Three Flags Ceremony was an interesting exercise in international relations. The Spanish governor, a Frenchman named Carlos deHault Delassus, raised the Spanish flag, then lowered it, to represent Spain's cession of the territory to France. Amos Stoddard, an American representing the French, raised the French flag. In deference to St. Louis' French populace, the flag flew overnight and was replaced by the American flag the next day (Stoddard now presiding as representative of the United States). Meriwether Lewis crossed over from his campsite at Wood River to attend the event, and he signed the transfer document as a witness. The residents of the Louisiana Territory (the European ones, that is) instantly became American citizens-whether they wanted to be Americans is another question.

America needed to resolve questions about the boundaries of the territory. The treaty signed in Paris simply stated that America was purchasing the territory with the same boundaries it had when it was held by Spain. The only problem was that no one could define those boundaries. Some Americans claimed the territory included Florida, Texas, and lands west of the Rockies. Spain didn't agree, and France didn't care. Jefferson defined the region as the watershed of the Missouri River-and it was imperative that Lewis and Clark find out exactly how far that area extended, especially since the region might include trade routes and lands claimed by Britain.

In his address at the opening of the 1904 Louisiana Purchase Exposition, Theodore Roosevelt stated that the Purchase was "the event which more than any other, after the foundation of the Government …determined the character of our national life." Stephen Ambrose notes that, for President Jefferson and the nation, the Purchase "increased infinitely the interest" in the Expedition. For Lewis and Clark, the Purchase transformed the nature of their expedition, converting it from a venture into foreign territory to a projection of American sovereignty over newly acquired lands-with all the adventure and controversy that entailed.

As the nation prepares to mark the bicentennials of the Louisiana Purchase and the Lewis & Clark Expedition, we should examine how these events transformed the life of the nation and of the peoples who lived in the Purchase lands. In Missouri, with its central role in both bicentennials, we have the privilege and the responsibility to stimulate public interest in the relationships between the Voyage of Discovery, the Louisiana Purchase, and the formation of the modern United States.