Answer:
Beginning in the 17th century, France explored the Mississippi River valley and established scattered settlements in the region. By the middle of the 18th century, France controlled more of the modern United States than any other European power: from New Orleans northeast to the Great Lakes and northwest to modern-day Montana. In 1762, during the French and Indian War, France ceded its America territory west of the Mississippi River to Spain and in 1763 transferred nearly all of its remaining North American holdings to Great Britain. Spain, no longer a dominant European power, did little to develop Louisiana Territory during the next three decades. In 1796, Spain allied itself with France, leading Britain to use its powerful navy to cut off Spain from America.
In 1801, Spain signed a secret treaty with France to return Louisiana Territory to France. Reports of the retrocession caused considerable uneasiness in the United States. Since the late 1780s, Americans had been moving westward into the Ohio and Tennessee River valleys, and these settlers were highly dependent on free access to the Mississippi River and the strategic port of New Orleans. U.S. officials feared that France, resurgent under the leadership of Napoleon Bonaparte, would soon seek to dominate the Mississippi River and access to the Gulf of Mexico. In a letter to Robert Livingston, the U.S. minister to France, President Thomas Jefferson stated, “The day that France takes possession of New Orleans…we must marry ourselves to the British fleet and nation.” Livingston was ordered to negotiate with French minister Charles Maurice de Talleyrand for the purchase of New Orleans.