11 Amazing Facts About the Louisiana Purchase

Several factors led to one of the biggest real estate bargains in American history, like Napoleon’s need for cash, some angry Mississippi River merchants, and (at least indirectly) Thomas Jefferson’s obsession with mastodons.
A detail of ‘Green River Cliffs, Wyoming, 1881’ by Thomas Moran
A detail of ‘Green River Cliffs, Wyoming, 1881’ by Thomas Moran / Gift of the Milligan and Thomson Families, National Gallery of Art // Public Domain
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On April 3, 1803, Napoleon reclined in a rose water-scented bath at Paris’s Tuileries Palace. It was where France’s self-declared emperor and power-hungry dictator conducted much of his scheming to conquer Europe. He wanted to rule Great Britain. But he was broke. And war with Britain appeared inevitable.

To generate cash quickly, Napoleon would turn to the United States and make the young nation an offer it would be foolish to turn down. Here are 10 essential facts about the Louisiana Purchase and how it shaped American history.

1. A revolt by enslaved people put the Louisiana Purchase in motion.

France formally acquired the colony of Saint Domingue (in modern-day Haiti) from Spain in 1697. For a century, it served as a major source of stable revenue for France. It grew and exported two-thirds of the country’s domestic product, including coffee, sugar, cotton, and indigo, produced by enslaved laborers on large plantations.

The high demand for products, and the inhumane conditions of the industries, fomented revolts by the enslaved workers and by free Black residents inspired by the ideals of liberté, egalité and fraternité then taking over France. When Napoleon sent French soldiers to quell the movements in the 1790s, the revolutionaries stood their ground, while yellow fever and malaria wiped out the troops. Those who survived returned home along with France’s hopes in the Caribbean, both defeated.

2. Thomas Jefferson wanted to prevent France and Britain from squeezing the U.S.

A map showing the U.S. and various European-controlled territories at the time of the Louisiana Purchase.
A map showing the U.S. and various European-controlled territories at the time of the Louisiana Purchase. / Dr. Boli, Flickr // CC BY 2.0

France needed another lucrative funding source for Napoleon’s ambitions. The emperor turned his attention to selling the Louisiana Territory—an enormous chunk of North America, the western watershed of the Mississippi River, that Spain had relinquished to France in 1800 in the secret Third Treaty of San Ildefonso. Napoleon didn’t have the military power to patrol this vast territory, and once France lost its Caribbean colonies, the North American land became a boondoggle.

President Thomas Jefferson, after becoming aware of the Third Treaty of Ildefonso in 1802, immediately wanted to avoid a situation in which the U.S. got squeezed between its enemies: British Canada to the north, French Louisiana to the west, and Spanish Florida to the south.

3. At first, Jefferson offered to buy New Orleans.

Before Spain had transferred the Louisiana Territory to France, it had signed a treaty with the U.S. giving merchants and farmers permission to send their goods down the Mississippi River and store them in New Orleans without paying extra taxes. After France took over Louisiana, it revoked these rights, infuriating American business owners.

Jefferson feared Napoleon’s plans for New Orleans and worried the U.S. would need British assistance to survive if Napoleon maintained control of the important port city. “The day that France takes possession of New Orleans … we must marry ourselves to the British fleet and nation,” Jefferson wrote to Robert Livingston, the U.S. minister to France.

Rather than go to war over the broken Mississippi River treaty, Jefferson told Livingston and former Minister to France James Monroe to negotiate with Napoleon to purchase New Orleans and West Florida. Napoleon, however, had by then decided to sell all of Louisiana to the U.S. to raise funds for his impending war with Britain.

4. The United States had to borrow money to complete the Louisiana Purchase.

The first page of the Louisiana Purchase treaty.
The first page of the Louisiana Purchase treaty. / Historical/GettyImages

Unfortunately, the United States didn’t have Napoleon’s final asking price: 60 million francs, or $15 million at the time (which included the forgiveness of France’s $3.75 million debt). The U.S. nation also had a debt of over $7 million. The House of Representatives passed bills allowing the U.S. to borrow money to complete the transaction with funds from British and Dutch banks; the terms of the agreements stipulated that the U.S. had 15 years to repay the loan.

5. The Louisiana Purchase was one of the biggest land bargains in American history.

When both countries signed the Louisiana Purchase treaty on May 2, 1803 (backdated to April 30), the boundaries of the Louisiana Territory were unclear. Livingston asked France’s Minister of Foreign Affairs Charles Maurice de Talleyrand where the borders were located. The Frenchman replied, “I can give you no direction. You have made a noble bargain for yourselves, and I suppose you will make the most of it.”

The actual geographic limits weren’t agreed upon until almost 20 years later, when the Convention of 1818 and the Adams-Onís Treaty of 1819 established the boundaries. According to A Wilderness So Immense: The Louisiana Purchase and the Destiny of America by John Kukla, the territory spanned the Mississippi River to the Rocky Mountains and from Canada to the Gulf of Mexico. It encompassed 13 present-day states: “Arkansas, Colorado east of the Rocky Mountains, Iowa, Kansas, Louisiana, Minnesota west of the Mississippi River, Missouri, Montana, Nebraska, North Dakota, Oklahoma, South Dakota, and Wyoming.”

It added 828,000 square miles (around 375 million acres) to the United States, doubling its size, at a cost of about four cents per acre.

6. Jefferson had secretly asked Congress for funds to investigate the Louisiana Territory—before the actual purchase.

On January 18, 1803, Jefferson sent a confidential letter to Congress requesting $2500 to fund an exploration of Louisiana. He realized that westward migration of American settlers would bring them into contact with Indigenous peoples, and he sought to encourage the Native peoples to adopt Western modes of trade and agriculture. Along with those goals, Jefferson wanted to know if there was a navigable water route to the Pacific Ocean—a Northwest Passage—to increase the nation’s trade with Asia.

As an avid naturalist, Jefferson also wanted a complete survey of the plants, animals, points of latitude and longitude, soil, and other characteristics of the territory.

7. Jefferson’s secretary formed the Corps of Discovery to explore the Louisiana Purchase.

George Catlin, ‘View in the ‘Grand Detour,’ Upper Missouri, 1861/1869’
George Catlin, ‘View in the ‘Grand Detour,’ Upper Missouri, 1861/1869’ / Paul Mellon Collection, National Gallery of Art // Public Domain

Jefferson appointed his personal secretary, army veteran Meriwether Lewis, to lead the Corps of Discovery, a group that eventually numbered 32 Army and civilian volunteers. To prepare for the journey, Lewis traveled to Philadelphia, the intellectual center of the young nation, to study under leading naturalists, botanists, and educators. Known for being brilliant yet moody, Lewis had a keen eye for detailing nature.

Lewis invited William Clark, his former commanding officer in the Army, to serve as his co-captain. “If therefore there is anything … which would induce you to participate with me in it’s fatiegues, it’s dangers and it’s honors, believe me there is no man on Earth with whom I should feel equal pleasure in sharing them as with yourself,” Lewis wrote in a letter dated June 19, 1803. Clark responded a month later, writing (with characteristic poor spelling and grammar), “This is an under takeing fraited with many difeculties, but My friend I do assure you that no man lives Whith Whome I would perfur to under take Such a Trip &c. as your Self.”

8. The corps kept voluminous diaries.

When Lewis and Clark’s expedition set out on May 13, 1804, they journaled each day. Whether they wrote 1000 words or six, as they did on the final day, no time went by without some account being recorded of their progress, discoveries, people, or weather. Anthony Brandt, editor of The Essential Lewis and Clark, estimates that between them, the two men wrote over 1 million words on their journey. Other members of their party also kept journals: enlisted men Patrick Gass, Joseph Whitehouse, John Ordway, and Charles Floyd recorded their personal experiences.

8. The Louisiana Purchase contained flora and fauna never before documented by European Americans.

Lewis and Clark recorded scientific accounts of grizzly bears.
Lewis and Clark recorded scientific accounts of grizzly bears. / William Campbell/GettyImages

From mid-May 1804, Lewis and Clark’s expedition lasted two years, four months, and 10 days and covered nearly 8000 miles of western North America. Historian Paul A. Johnsgard, in Lewis and Clark on the Great Plains: A Natural History, has suggested that Lewis and Clark recorded nearly 100 “previously unknown species or subspecies of vertebrate animals,” including mammals like the pronghorn, black-tailed prairie dog, grizzly bear, swift fox, mule deer, and white-tailed jackrabbit. A prairie dog was captured and sent 4000 miles east to be exhibited in an exposition at the Philadelphia Museum.

In their crossing of the Great Plains, the corps also scientifically documented birds like the greater sage-grouse, western meadowlark, common poorwill, least tern, and Lewis’s woodpecker, named after the corps’s co-leader. (That species, along with another bird named Clark’s nutcracker, will likely be renamed by the American Ornithological Society as part of a new plan to de-emphasize historical eponyms.)

9. The corps met—and were helped by—Indigenous tribes who lived within the Louisiana Territory.

Lewis and Clark’s party encountered between 50 and 65 Native nations on their journey, including the Iowa, Osage, Kansa, Pawnee, Lakota, Cheyenne, Crow, Blackfeet, Nez Perce, Shoshone, and Clatsop. Some were already friendly with white traders or trappers and offered their assistance to the corps. Mandan and Hidatsa villages hosted the expedition during the winter of 1804-1805, at which time the corps hired its interpreters Toussaint Charbonneau and his wife, Sacagawea. The Nez Perce guided the corps through the Rocky Mountains and the Clatsop became frequent visitors at the corps’s fort on the Oregon coast during the winter of 1805-1806. Many provided essential information, food, and supplies to the expedition.

Not all tribes accommodated the explorers, however. The white men’s presence was a nuisance to some, disrupting their hunts and diplomatic relations with their neighbors. And some leaders recognized that the expedition’s presence signaled the detrimental waves of white settlers to come.

10. Lewis and Clark weren’t the only ones to explore the Louisiana Territory.

Zebulon Montgomery Pike
Zebulon Montgomery Pike, explorer of the Louisiana Territory / Historical/GettyImages

Jefferson organized two other exploring trips to survey the lands of the Louisiana Purchase. The Dunbar-Hunter expedition, led by Scottish gentlemen naturalists William Dunbar and George Hunter, paddled up the Ouachita River in present-day Louisiana and Arkansas in 1804–1805, recording the flora and fauna. Two scientists, Thomas Freeman and Peter Custis, explored the Red River through present-day Louisiana in 1806, hoping to establish ties with the Indigenous settlements on the way. A third expedition was launched by Louisiana Governor James Wilkinson. From 1806 to 1807, a group led by Zebulon M. Pike headed from St. Louis through present-day Kansas into the Rocky Mountains to find the source of the Red River. Pike’s group was captured by Spanish troops, taken to Chihuahua, Mexico, and eventually released.

11. To Jefferson’s dismay, the Louisiana Purchase didn’t yield any live mastodons.

The expeditions’ experiences disproved some legends about the West. Jefferson had hinted to Lewis that the corps may encounter “Welsh Indians,” a group supposedly descended from a Welsh prince named Madog ab Owain Gwynedd. According to folklore, Madog sailed to North America in the 12th century and traveled up the Missouri River; his descendants were thought to be an extant community of Welsh-speaking “white Indians.” (The popularity of the myth in Jefferson’s time stemmed from racist views of Indigenous people as well as the territorial ambitions of Britain and Spain.) Lewis and Clark, of course, didn’t run into any such folks.

The president also believed in a then-popular, quasi-scientific theory called the Great Chain of Being. One of its tenets proposed that all nature was created by God in its complete and final hierarchical form. No part of this web of nature could be destroyed; extinction of species was not possible. Thus, when Jefferson’s friend, the artist Charles Willson Peale, exhumed mastodon bones from a farm in upstate New York in 1801, Jefferson—who had been obsessed with mastodons for some time—hoped that Lewis and Clark would find a live specimen on their journey out west. We know now that mastodons went extinct about 10,000 years before the Louisiana Purchase.