Westward Expansion · Topic 1 · Grades 6-8
About 30 people in a few boats set out to cross a continent that was already home to dozens of nations. What did they find, who helped them, and how do we know?
In May 1804 a small army unit called the Corps of Discovery pushed off up the Missouri River. They didn't know whether they would come back. Two and a half years later, people in St. Louis cheered as their canoes came around the bend. In between, the Corps paddled, dragged and pushed boats against the current, crossed the Rocky Mountains on foot and horseback, and reached the Pacific coast. They would not have made it without the help of the Native nations who lived along the way.
On this page you will: learn why President Jefferson sent the expedition, follow its route on a map and a timeline, meet the people who made the trip possible, read the travelers' own words, and think about how historians know what happened.
By 1803 the United States stretched from the Atlantic Ocean to the Mississippi River. (For how it got that far, see Paul's Early American History course.) West of the Mississippi lay land the United States knew little about. President Thomas Jefferson wanted to change that.
On April 30, 1803, the United States agreed to buy the Louisiana Territory from France. It covered about 828,000 square miles and cost $15 million, less than 3 cents an acre. It doubled the size of the country.
What the United States really bought was France's claim to the region. Dozens of Native nations already lived there, and nobody had asked them.
Jefferson had been planning the trip before the purchase was even signed. In January 1803 he asked Congress for $2,500 to pay for it. He picked his secretary, army captain Meriwether Lewis, to lead it. On June 20, 1803, he wrote Lewis a long letter of instructions:
"The object of your mission is to explore the Missouri river, & such principal stream of it, as, by it’s course & communication with the waters of the Pacific ocean, may offer the most direct & practicable water communication across this continent, for the purposes of commerce."
Thomas Jefferson to Meriwether Lewis, June 20, 1803 (original spelling)
Jefferson also told Lewis how to treat the people he met. His own nation was claiming their land, but he wrote:
"In all your intercourse with the natives, treat them in the most friendly & conciliatory manner which their own conduct will admit"
Jefferson's instructions to Lewis, June 20, 1803 (original spelling). Intercourse here means "dealings"; conciliatory means "trying to keep the peace."
Lewis asked his friend William Clark to share command. The army only made Clark a lieutenant, but Lewis treated him as an equal, and the men called both of them "Captain."
The Corps traveled up the Missouri River, over the Rocky Mountains and down the Columbia River to the Pacific. The Library of Congress estimates the round trip at about 8,000 miles. Today the Lewis and Clark National Historic Trail runs nearly 4,900 miles through the homelands of more than 60 Tribal nations. Select a numbered circle to jump to that stop on the timeline.
Each numbered event matches a circle on the map. Quotes are copied in the writers' original spelling. Spelling wasn't standardized yet, and the captains wrote fast, often in bad conditions.
Up the Missouri, 1804-1805
Camp Dubois, Illinois, across the Mississippi from the mouth of the Missouri
The Corps spent the winter of 1803-1804 training at Camp Dubois. In May it set off up the Missouri River in a large keelboat and two smaller boats called pirogues. Going upstream meant rowing, poling, and sometimes pulling the boats with ropes from the shore.
Council Bluff, north of present-day Omaha, Nebraska
Lewis and Clark held their first formal meeting with Native leaders, from the Oto and Missouria nations. The captains gave speeches and gifts, including peace medals, and told them that the United States was now in charge of the land. They held many meetings like this along the way.
Near present-day Sioux City, Iowa
Sergeant Charles Floyd became very sick, probably from a burst appendix. Doctors of the time did not know how to treat it. He was the only member of the Corps to die on the expedition.
"Serj.' Floyd Died with a great deel of Composure, before his death he Said to me, "I am going away" ["]I want you to write me a letter"—"
William Clark, August 20, 1804 (original spelling)
Mouth of the Bad River, near present-day Pierre, South Dakota
The Lakota (whom the captains called Teton Sioux) were a powerful nation that controlled trade on this part of the river. Talks went badly, partly because, as Clark admitted, "(we discover our interpeter do not Speak the language well)." Young Lakota men held onto the boat's rope, and both sides readied weapons. Then a leader the captains called Black Buffalo stepped in: "The grand Chief then took hold of the Cable & Sent all the young men off." No one was hurt.
Near the Knife River, present-day North Dakota
The Corps reached the Mandan and Hidatsa villages in late October 1804. About 4,500 people lived there, more than in St. Louis at the time. The villages were a busy trading center. The Corps built Fort Mandan nearby and spent a freezing winter there, trading with their neighbors for corn.
In November the captains hired Toussaint Charbonneau, a French-Canadian trader living among the Hidatsa, as an interpreter. His young Shoshone wife, Sacagawea, came too. On February 11, 1805, she gave birth to a son, Jean Baptiste.
Leaving Fort Mandan
The keelboat went back down the river with reports, maps and specimens for Jefferson. The permanent party of 33 people, including Sacagawea and her baby, headed upriver in six small canoes and two pirogues.
"This little fleet altho' not quite so rispectable as those of Columbus or Capt. Cook were still viewed by us with as much pleasure as those deservedly famed adventurers ever beheld theirs"
Meriwether Lewis, April 7, 1805 (original spelling)
The same day Lewis wrote that they were entering a country "on which the foot of civillized man had never trodden." Think about it: people had lived on that land for thousands of years. Whose point of view does his sentence show?
Over the mountains, 1805
Great Falls, Montana
Lewis heard a roar and saw spray rising. The waterfall "formes the grandest sight I ever beheld," he wrote. But there were five falls, not one. The Corps had to portage (carry the boats and supplies over land) about 18 miles around them. It took about a month, in heat, hail and prickly pear cactus. Sacagawea was very ill there for days.
Lemhi Pass, on today's Montana-Idaho border
Lewis walked ahead to find the Shoshone and their horses. He reached a spring he believed was the source of the Missouri:
"the road took us to the most distant fountain of the waters of the mighty Missouri in surch of which we have spent so many toilsome days and wristless nights."
Meriwether Lewis, August 12, 1805 (original spelling)
From the top of the pass he saw more mountains, not the easy water route Jefferson hoped for.
Camp Fortunate, on the Beaverhead River, Montana
A few days earlier, Sacagawea had recognized a landmark from her childhood. Now, when the Shoshone leader Cameahwait came to meet the captains, she realized he was her brother.
"the Indian woman, who proved to be a sister of the Chif Cameahwait. the meeting of those people was really affecting"
Meriwether Lewis, August 17, 1805 (original spelling)
The Shoshone traded horses to the Corps. Without them, the Corps could not have crossed the mountains.
Bitterroot Mountains, Idaho
A Shoshone guide the captains called Old Toby led them over the Bitterroots on the Lolo Trail. Snow fell, game was scarce, and the men grew weak with hunger. On September 14 they killed one of their colts to eat.
"I have been wet and as cold in every part as I ever was in my life"
William Clark, September 16, 1805 (original spelling)
Weippe Prairie and Canoe Camp on the Clearwater River, Idaho
Clark and a few hunters came out of the mountains onto a prairie where the Nez Perce (Nimiipuu) were camped. "those people treated us well gave us to eate roots," he wrote. The men built dugout canoes at Canoe Camp, and the Nez Perce agreed to care for the Corps' 38 horses until spring.
Nez Perce oral tradition adds something the captains never knew. A woman named Watkuweis had been captured as a girl and had lived for a time among white people far to the east, who treated her well. When some people discussed killing the weak strangers, she told them: "These are the people who helped me. Do them no hurt."
To the Pacific, 1805-1806
Lower Columbia River, Washington
On the way down the Columbia, Clark noticed something about Sacagawea: "a woman with a party of men is a token of peace." Then, on November 7:
"Great joy in camp we are in View of the Ocian, … this great Pacific Octean which we been So long anxious to See."
William Clark, November 7, 1805 (original spelling)
Clark was actually looking at the wide estuary of the Columbia, still about 20 miles from the open ocean. On November 24 the party voted on where to spend the winter. York and Sacagawea both had a say, which was very unusual for an enslaved man and a Native woman in 1805.
Near present-day Astoria, Oregon
The Corps built a small log fort near the Clatsop people and named it for them. On Christmas Day, Clark wrote that "all our party moved into their huts." It rained almost every day. The men made salt, sewed moccasins and traded with the Clatsop and Chinook.
Not every trade was fair. When the Clatsop wouldn't sell a canoe, the Corps took one, saying it was payment for elk they believed had been stolen from them. But the Clatsops had already paid for the missing elk with dogs, and the National Park Service says Coboway had brought presents to make up for them. On March 18, four men took the canoe and hid it near the fort while Coboway was visiting. The National Park Service says the captains "broke the trust established through months of friendship and trade." When the Corps left, they gave the fort to the Clatsop leader Coboway.
The trip home, 1806
Nez Perce country, then Travelers' Rest, near present-day Missoula, Montana
Back in Nez Perce country, the Corps waited about a month for the snow in the mountains to melt. Nez Perce guides led them back across. On July 3, at a campsite called Travelers' Rest, the captains split up to explore more land. Lewis headed northeast toward the Marias River, and Clark headed southeast toward the Yellowstone River.
Yellowstone River, near present-day Billings, Montana
Clark climbed a tall sandstone rock and carved his name and the date into it.
"This rock which I shall Call Pompy's Tower is 200 feet high"
William Clark, July 25, 1806 (original spelling)
"Pompy" was Clark's nickname for Sacagawea's son. The rock is now called Pompeys Pillar, and Clark's carving is still there. It is the only physical evidence of the expedition you can still see along the trail.
Northern Montana
Lewis's small group of four camped with eight Piegan Blackfeet men. At dawn the Piegan tried to take the Corps' guns and horses, and a fight broke out. At least one Piegan was killed. The sources disagree about whether a second man died. Before riding off, Lewis left a peace medal around the dead man's neck "that they might be informed who we were," he wrote (original spelling). It was the only deadly fight of the expedition.
Missouri River, below the mouth of the Yellowstone, North Dakota
Lewis's and Clark's groups met again on the Missouri. From here the current was with them, and the canoes moved quickly downstream.
St. Louis, Missouri
Sergeant John Ordway wrote that they arrived "about 12 oClock":
"the people gathred on the Shore and Huzzared three cheers"
John Ordway, September 23, 1806 (original spelling)
"the party all considerable much rejoiced that we have the Expedition Completed," he added.
The expedition is named for two men, but it took many more people to make it work, and the people who already lived in the West shaped every step.
Captain, from Virginia
Jefferson's secretary before the trip. He studied science and medicine to prepare, and wrote long descriptions of plants and animals.
Co-captain, from Virginia and Kentucky
An experienced army officer and the expedition's main mapmaker. He kept a journal almost every day.
Enslaved by William Clark
York hunted, traded and did the same hard work as the soldiers, and he had a vote at the Columbia in 1805. Yet he got no pay and no land. After the trip he asked Clark for his freedom, and Clark refused. Years later, in 1832, Clark said he had freed York. The National Park Service says York was freed sometime after 1815. In 2001, President Clinton made York an honorary sergeant.
Lemhi Shoshone interpreter
As a girl she was captured in a Hidatsa raid and taken far from home. She was about 16 when she joined the Corps with her baby. She was not the guide who led them west, as some stories claim. She helped by translating and recognizing landmarks, and her presence showed other nations that the group came in peace. Historians debate what happened to her later, but most believe she died at Fort Manuel Lisa, in present-day South Dakota, before she turned 30.
The youngest traveler
Sacagawea's son was born at Fort Mandan and carried across the continent as a baby. Clark nicknamed him "Pomp" or "Pompy."
Interpreter
A French-Canadian fur trader who had lived among the Hidatsa. He was Sacagawea's husband.
About two dozen men
They included Sergeant Charles Floyd, who died in 1804, and Sergeants John Ordway and Patrick Gass, who kept journals of their own.
These are only a few of the nations whose homelands the Corps crossed. Many of them still live there today.
Met the captains at the first council in August 1804.
A powerful nation that controlled trade on the middle Missouri. Black Buffalo calmed the 1804 standoff.
Farmers and traders whose busy villages fed and sheltered the Corps through its first winter.
Sacagawea's people. Cameahwait's band traded the horses the Corps needed, and Old Toby guided them over the mountains.
Welcomed the Corps in the Bitterroot Valley and traded more horses. Clark wrote that "those people recved us friendly."
Fed the starving travelers, looked after their horses all winter, and guided them back over the mountains in 1806.
Lived near the mouth of the Columbia, traded food and goods with the Corps all winter, and were skilled canoe builders.
A powerful nation of the northern plains. Their young men met Lewis's group at the Two Medicine River in 1806.
Every quote on this page is copied from the expedition journals or Jefferson's letter, with the writers' original spelling and punctuation. Read these aloud with a partner. What do they show about each writer's feelings and point of view?
"The Great Chief of this nation proved to be the brother of the Woman with us"
William Clark, August 17, 1805
"those people recved us friendly, threw white robes over our Sholders & Smoked in the pipes of peace"
William Clark, about the Salish, September 4, 1805
"The wife of Shabono our interpetr we find reconsiles all the Indians, as to our friendly intentions a woman with a party of men is a token of peace"
William Clark, about October 13, 1805. "Shabono" is Clark's spelling of Charbonneau.
Historians piece together the story from several kinds of evidence. Each one has strengths and blind spots.
Think like a historian: When two sources disagree, as they do about the Two Medicine fight, historians don't just pick one. They say what each source claims and explain what remains uncertain.
A gust of wind has scattered six pages from the expedition's records. Can you put them back in the order they happened?
Move each page with the ▲ and ▼ buttons, or tap a page and then tap where it belongs. With a keyboard, Tab to a page, press Space to pick it up, move it with the ↑ ↓ arrow keys, and press Space again to drop it. Put the earliest event at the top.
You get 1 point for each page in the right position, so a perfect round is 6 points. Your total adds up across rounds. Your best total is saved only in this browser. Each new round deals 6 pages at random from 15 events.
Ten questions. Choose one answer for each, then check your score. You can try as many times as you like.
Written by Meriwether for Jugami's Westward Expansion course. The route map and icons are original SVG drawings made for this page. The map's rivers and stops are placed by hand from approximate latitudes and longitudes. Quotes keep the original spelling from the published journals and letters. Built with plain HTML, CSS and a little JavaScript, with no trackers and no ads. Last checked October 2026.
