In summer 1804, Meriwether Lewis and William Clark left St. Louis and embarked on an 8000-mile journey across North America. President Thomas Jefferson had instructed their Corps of Discovery to explore parts of the continent west of the Mississippi River, which the United States had recently purchased from France, and find a navigable river route to the Pacific Ocean.
They didn’t find it—but they did return with journals full of observations, new maps of previously uncharted lands, information about Native peoples’ communities and customs, and the evidence to support the country's westward expansion. Here are 12 facts about the Lewis and Clark expedition.
1. President Thomas Jefferson secretly requested funds for the expedition.
The first years of the 19th century were fraught with delicate diplomatic negotiations between the young United States and European nations. Spain, which owned Louisiana and the port of New Orleans, had allowed the U.S. to ship goods on the Mississippi River in peace. In 1800, France bought Louisiana from Spain. American leaders were alarmed at Napoleon Bonaparte’s plans for reestablishing the French empire at such a valuable port and impeding America’s westward expansion. Great Britain also had designs on the territory.
The U.S. understood the political dynamite at hand. Jefferson directed James Monroe and Robert Livingston, the U.S. minister to France, to negotiate the purchase of New Orleans from Bonaparte. Around the same time, Jefferson secretly requested $2500 from Congress (about $61,800 in today’s dollars) for an expedition to “[extend] the external commerce of the United States.” The House took up the matter with “an injunction of secrecy” and passed it in February 1803.
Meanwhile, the successful rebellion by enslaved people in France’s colony of St. Domingue (modern-day Haiti) changed Bonaparte’s plans. To raise money for his government, he offered not just New Orleans, but one of France’s gigantic chunks of North America—totaling 830,000 square miles—to Monroe and Livingston for the bargain price of $15 million, not including interest (about $371 million today).
2. The Corps was tasked with finding a river route to the Pacific Ocean.
Jefferson accepted the deal without consulting anyone; Monroe and Livingston signed the Louisiana Purchase Treaty on May 2, 1803, in Paris. (The Senate later approved the treaty.)
The purchase doubled the size of the United States, paving the way for Jefferson to stake a long-sought claim to the West. Following Congress’s $2500 appropriation, the president tapped Meriwether Lewis, his 28-year-old personal secretary and a former soldier, to command the expedition to establish trade and relations with the Native peoples of the newly acquired lands and look for a navigable water route connecting the Mississippi River to the Pacific Ocean. Lewis chose William Clark, a 33-year-old militia officer, to be the co-leader of the Corps of Discovery.
3. Technically, Lewis was Clark’s superior.
Lewis had served under Clark in several military battles, and respected him so much that he wanted Clark to be commissioned as his co-commander on the expedition. The U.S. secretary of war denied request, but the two men chose to keep up the appearance of a shared command. They referred to each other as “captain” so the other members wouldn’t know the difference.
4. Lewis paid $20 for the expedition’s dog.
While in Pennsylvania preparing for the trip, Lewis spent $20 on a Newfoundland dog, who is believed to have completed the entire journey with the explorers. There is some debate among historians about the dog’s name, though most modern accounts refer to him as Seaman; other interpretations are Scannon or Seamon.
In a November journal entry, Lewis wrote that members of the Shawnee and Delaware tribes wanted to trade for the dog. In denying their offer, Lewis mentioned the $20 price tag and that he valued the dog for “his docility and qualifications for my journey.”
Lewis and Clark named “Seaman’s Creek” in Montana for the dog, but it never became official. It’s known as Monture Creek today.
5. The Corps of Discovery began its journey at the confluence of the Missouri and Mississippi rivers.
The expedition launched from Camp Wood north of St. Louis in May 1804. More than 40 men started the journey, including the two co-captains, a hired boat crew, and members (primarily from Virginia and Kentucky) with experience in surveying, blacksmithing, hunting, and other outdoor skills. Only one member, Sergeant Charles Floyd, died during the expedition, possibly of a ruptured appendix. His grave in Iowa is now marked with a 100-foot stone obelisk.
6. An enslaved man was part of the Corps of Discovery.
Along with the expedition members, soldiers, and interpreters who would join the crew, Clark chose his “body servant,” an enslaved man named York, to make the trip. Clark had inherited York from his father.
York was the only Black man in the Corps of Discovery. He defended the men, hunted—which was unusual because enslaved people were rarely allowed to use firearms—and reportedly had a vote in expedition matters. He was important in relations with tribes, many of whom had never seen a Black man and were intrigued by him.
When the expedition made it back east, York asked Clark for his freedom as payment for his two years of labor. Clark refused. When York proposed moving to Louisville, Kentucky, as a hired hand to join his wife there, Clark refused that request as well.
7. Sacagawea was the only woman on the expedition.
Sacagawea, the daughter of a Shoshone chief in what is now Idaho, had been captured by their enemies, the Hidatsa, when she was about 12. While with the Hidatsa in present-day North Dakota, she was sold or bartered to Toussaint Charbonneau, a French-Canadian trapper living with the tribe. Charbonneau took Sacagawea as one of his wives.
Lewis and Clark met Sacagawea, then about 17, when they reached the Hidatsa-Mandan settlement in November 1804. They hired Charbonneau as an interpreter and brought Sacagawea on as well, because she could speak Shoshone and Hidatsa and help them negotiate with the people they met on their journey. She also helped identify edible plants and navigate over the Bitterroot Mountains.
The Corps of Discovery built Fort Mandan nearby and wintered there before departing again in the spring of 1805—two months after Sacagawea gave birth to a son, Jean Baptiste. While it may not seem logical to take a newborn on such a grueling expedition, historians have suggested that the presence of a Native woman and baby among the men helped the corps appear non-threatening.
8. Spain tried to intercept and arrest Lewis and Clark.
Spain still owned a huge amount of land in North America, including a swath from present-day eastern Texas to the Columbia River in the Pacific Northwest. The Spanish government, afraid that Lewis and Clark would threaten their claim to gold in the Southwest, sought to thwart the expedition. Former Revolutionary War general James Wilkinson, a spy for Spain known as agent Number 13, sent coded messages to Spain’s leaders warning them of the expedition. Wilkinson urged his handlers to “detach a sufficient body of chasseurs to intercept Captain Lewis and his party, who are on the Missouri River, and force them to retire or take them prisoners.” Spain did—but failed to find the expedition.
9. Members of the expedition sometimes ate dog meat.
The expedition stocked its keelboat with seven tons of nonperishable foods, including flour, beans, dried pork, sugar, coffee, salt, corn, and lard. They even took “portable soup,” made by boiling down broth to the consistency of glue and then drying it in rubbery pieces that could be reconstituted later. Protein, however, sometimes became scarce. The men hunted, fished, and traded with tribes for any kind of meat. At times, this included dogs. The expedition managed to spare the life of their Newfoundland Seaman, though.
10. The expedition gathered 200 botanical specimens and introduced 122 animals to Western science.
Lewis and Clark kept extensive journals of their observations. They’re credited with recording 122 animals new to Western science and collecting more than 200 botanical specimens during the journey. While Native people who live in the regions where the expedition traveled have known about these flora and fauna since time immemorial, Lewis and Clark showed evidence of the plants and animals to scholars in the East for the first time.
Their animal descriptions included grizzly bears, prairie dogs—which Lewis proposed calling “barking squirrels”—coyotes, jackrabbits, and pronghorn. Among their botanical specimens were bitterroot, ponderosa pine, and Douglas fir. They did not find a live mastodon, much to Jefferson’s regret.
11. The Lewis and Clark expedition lasted more than two years.
Lewis and Clark continued their navigation of the Missouri River and its tributaries until reaching the Continental Divide in present-day Montana. The Corps crossed the Rocky Mountains on horseback, then descended the Columbia River to the Pacific coast. They spent the rainy winter of 1805-1806 at Fort Clatsop, a compound they built at the mouth of the Columbia, and became friendly with the Native people in the region.
In March 1806, they began the long trip back to St. Louis. At Lolo Pass in the Rockies, Lewis and Clark split up; Lewis and a group of men took the trail they blazed on the first leg of their journey and explored river systems in northwest Montana. Clark and his party went south and east along the Yellowstone River. They reconvened on the Missouri north of their old Fort Mandan in North Dakota and began their downstream voyage. Finally, on September 23, 1806, they pulled into St. Louis, having traveled almost 8000 miles.
12. Lewis died three years after the expedition under mysterious circumstances.
Lewis was then governor of the Upper Louisiana Territory and was on a trip along the Natchez Trace, a route that ran from Mississippi to Tennessee. He stopped at an inn run by the Grinder family, and before morning, he was dead from two gunshot wounds to the head and abdomen.
Most, but not all, historians have concluded he died by suicide due to the circumstantial evidence: Lewis was known to have depressive episodes, drank heavily, and was having financial trouble. He had reportedly attempted to take his own life prior to the trip, and had also drafted a will while on the journey.
Others are convinced he was murdered and question Mrs. Grinder’s statement; she said she heard gunshots and saw Lewis stagger outside (though she didn’t help him). Some theorize that Mr. Grinder or one of the bandits that roamed the Natchez Trace shot him. Whatever the real cause of death, Lewis was buried in Hohenwald, Tennessee, where a monument was later erected in his honor.