At the turn of the nineteenth century, the western border of the United States ended at the Mississippi River. The area comprising the western half of the young nation and the vast territory beyond had originally been settled by France in the seventeenth century; the French had explored and claimed the land from the mouth of the St. Lawrence River and the Great Lakes to the north to the Mississippi River and New Orleans in the south. They controlled the territory through a series of forts, trading posts, missions, and settlements that were anchored by the major cities of Montreal, Quebec, Detroit, and New Orleans. The French lost control of its North American territory to Spain and Great Britain following its defeat in the French and Indian War (1754–1763). France ceded control of New Orleans and Louisiana west of the Mississippi to Spain in 1762. It yielded control of its territory east of the Mississippi River to Great Britain the following year; this territory became part of the United States when it gained its independence from Great Britain in 1783. Under an agreement with Spain, the United States was allowed to conduct commerce along the Mississippi River and had access to the important port of New Orleans.
Napoléon Bonaparte (1769–1821) took power in France in 1799. The man who would become emperor of France in 1804 wanted to reclaim the North American territory France had lost, and he negotiated a series of secret agreements with Spain in 1800. Under the Treaty of San Ildefonso, Spain would cede control of the Louisiana Territory to France six months after certain other conditions of the treaty had been met. In October 1802, Spain closed the port warehouses of New Orleans to American trade in violation of its treaty with the United States.
The loss of the port was devastating to U.S. international trade, prompting some factions to call for war with France. U.S. president Thomas Jefferson (1743–1826) was alarmed by the prospect of having the powerful and aggressive French presence as a neighbor but wanted to resolve the situation through diplomacy. Jefferson decided to send James Monroe (1758–1831), ambassador to Great Britain, to join Robert Livingston (1746–1813), ambassador to France, in Paris to negotiate the purchase of land that would secure access to important ports for American trade. If the purchase was not an option, Jefferson hoped to garner rights for Americans to navigate the Mississippi River. He authorized Monroe to pay up to $10 million for New Orleans as well as all or part of Florida.
Monroe joined Livingston in Paris on April 12, 1803, to discover that the France’s plans for its North American territory had changed significantly since the Treaty of San Ildefonso. Napoléon was determined to control Europe, and he engaged in a series of wars with the other powers on the continent throughout the first decade of the nineteenth century, most notably with Great Britain. Although the Treaty of Amiens had established a temporary peace between the two countries in 1802, war would break out anew in May 1803.
Napoléon’s focus on Europe coincided with a significant defeat by the French army on the island of St. Domingue (present-day Haiti); slaves and free blacks there staged a successful rebellion that resulted in the withdrawal of French troops in 1803 and the island’s independence from French rule in 1804. The loss of its most important colony diminished the value of France’s other territory in the western hemisphere. France could not afford to send enough troops to the Louisiana Territory to defend it from attack by British forces in Canada, particularly if the Americans decided to join Great Britain in the war in order to reclaim their trading rights on the Mississippi River. France’s minister of finance, François de Barbé-Marbois (1745–1837), advised Napoléon to sell the entire territory outright to the United States. Napoléon agreed, and the French foreign minister Charles Maurice de Talleyrand (1754–1838) made the offer to Livingston on April 11, 1803, the day before Monroe’s arrival.
Monroe and Livingston had not been authorized to negotiate such a large purchase, but they felt that they could not afford the delay that would be required in an exchange of correspondence across the Atlantic to wait for approval from Jefferson. On April 30, 1803, Monroe, Livingston, and Barbé-Marbois signed a treaty in Paris that exchanged fifteen million dollars for a vast swath of land stretching from present-day Montana to New Orleans. The purchase payment came out to about four cents an acre. They notified Jefferson in time for the official announcement of the treaty on July 4, 1803. The Louisiana Purchase treaty was ratified by the Senate on October 20, 1803. On December 20 of the same year, the flag of the United States was unfurled in the city of New Orleans, representing the transfer of control of the Louisiana Territory from France to the United States.
The Louisiana Purchase encompassed all of the area between the Mississippi River and the Rocky Mountains: the present-day states of Arkansas, Iowa, Kansas, Missouri, Nebraska, and Oklahoma, and parts of Colorado, Louisiana, Minnesota, Montana, New Mexico, North Dakota, South Dakota, Texas, and Wyoming. It doubled the size of the United States at the time. In addition to a major change in the size of the United States, the acquisition represented a shift in philosophy for Jefferson, who had advocated a strict constructionist view of the Constitution. The Constitution did not include any provisions for acquiring territory, and some leaders within the Democratic-Republican Party viewed Jefferson’s action as unconstitutional. Jefferson’s purchase showed his willingness to use the power of the presidency and set a precedent for strong presidential leadership.
Despite the U.S. flag flying in New Orleans, many of its inhabitants were descendants of the territory’s original French explorers and still considered themselves to be French citizens. President Jefferson sent William Charles Cole Claiborne (1772–1817), the first territorial governor, and General James Wilkinson (1757–1825), along with five hundred regular troops and militiamen, to Louisiana to take possession of the newly acquired territory. Unlike the previously established American territories where the residents primarily spoke English, Louisiana inhabitants spoke many different languages, practiced a variety of religions, and had little experience with a representative-style government. Over the next decade, many Americans moved to the Louisiana Purchase area and claimed the land physically for the United States, although French influence remains in Louisiana to this day.
In hindsight, the Louisiana Purchase is considered to be Thomas Jefferson’s greatest achievement. The Lewis-Clark expedition that explored the Louisiana Territory and beyond from 1804 to 1806 revealed the land’s vast natural resources. Americans poured into the new territory to establish farms. Most of the nineteenth century would be devoted to securing the land for settlement by subjugating the Native American tribes living in the territory. The acquisition and subsequent settlement of the territory spurred the dream of “Manifest Destiny” in which Americans believed it was their destiny to expand their borders across the entire continent to the west coast.
Although the Louisiana Purchase had averted conflict with France and resolved the trade crisis, the lack of defined boundaries in the treaty created territorial disputes with Spain. The Spanish claimed the area purchased only consisted of the west side of the Mississippi and New Orleans. The United States laid claim to land all the way up to the Rio Grande and the Rocky Mountains. With this claim, the United States would acquire all of Texas and part of New Mexico, which included Spanish colonies. The Spanish opposed the Louisiana Purchase in whole because they had an agreement with France not to give the land over to a third party. The matter would not be settled completely until 1821 and the signing of the Transcontinental Treaty.
The Louisiana Purchase created internal divisions as well. As the territory began to be divided into states, Northern and Southern politicians debated the expansion of slavery. Louisiana had entered the Union as a slave state in 1812; when Missouri attempted to do the same in 1818, Northern politicians feared that its inclusion as a slave state would upset the balance of power between the free and slave states since Missouri would give the slave states a majority representation in the federal government. Henry Clay (1777–1852), a U.S. senator from Kentucky, managed to calm the tense standoff between the proslavery and antislavery factions by suggesting that Maine enter the Union as a free state, thereby restoring the balance of power in what became known as the Missouri Compromise of 1820. The agreement mandated that territories north of the 36°30′ parallel would enter the Union as free states, while territories south of that line would enter as slave states. The Compromise would be discarded by the Kansas-Nebraska Act of 1854, when it was determined that the people living in the territories of Kansas and Nebraska could decide for themselves whether to enter the Union as free or slave states. While Nebraska was too far north to enter as a slave state, the ensuing violent struggle for control of Kansas by antislavery and proslavery forces was a harbinger of the ultimate struggle over slavery that would be fought during the American Civil War (1861–1865).