The Timeline
Click any entry to expand the full account — journal entries quoted verbatim.
On a rainy Monday morning, 33 men pushed off from Camp Dubois into the Missouri River. Clark commanded the 55-foot keelboat carrying weapons, medicine, scientific instruments, and nearly a ton of gifts intended for Native nations. Lewis watched from shore and rejoined downstream after finishing last-minute business in St. Louis.
Jefferson's instructions had been exact: map the rivers, catalogue every plant and animal, make peaceful contact with every tribe, and find a water route to the Pacific. Nobody in Washington knew how far that route was — or whether it existed. Most of the men had never been west of the Mississippi.
"I set out at 4 oClock P.M. in the presence of many of the neighbouring inhabitants, and proceeded on under a jentle breese up the Missourie."
— William Clark · May 14, 1804
Library of Congress / Wikimedia Commons — Public Domain
Lewis and Clark held their first formal meeting with Native American leaders on a shaded hill above the Missouri. Representatives of the Otoe and Missouria nations listened to Lewis's prepared speech announcing American sovereignty over the land. The speech was translated through three languages, losing nuance at every step.
The chiefs accepted Jefferson Peace Medals — silver coins with Jefferson's face on one side and clasped hands on the other. What they privately made of the American claim to land their people had lived on for generations is not recorded in the journals. This diplomatic template would be repeated at dozens of councils across the continent.
Sergeant Charles Floyd died — almost certainly from a ruptured appendix, untreatable anywhere in the world in 1804. Lewis, trained by Dr. Benjamin Rush, did everything possible. Floyd was buried on a bluff with full military honors; Clark named the nearby creek after him.
Remarkably, Floyd would be the only Corps member to die on the entire 28-month, 8,000-mile journey — an extraordinary record for a wilderness expedition of 33 people.
"Died with a great deel of Composure, haveing Said to me before his death that he was going away and wished me to write a letter &c."
— William Clark · August 20, 1804The Teton Sioux were the most powerful nation on the northern plains. When warriors grabbed the rope of a pirogue and demanded a boat as tribute, Lewis ordered the cannon aimed at shore. Clark drew his sword. Thirty armed Sioux stood their ground. For several long minutes, neither side moved.
Then Chief Black Buffalo stepped forward, ordered his warriors back, and released the rope. Lewis and Clark recorded it as the most dangerous moment they had faced. They were right.
"I felt My Self warm & Spoke in very positive terms… The chiefs were not satisfied, haiveing every expectation of reciving goodes."
— William Clark · September 25, 1804The Corps built Fort Mandan near the Mandan and Hidatsa villages on the upper Missouri. Temperatures dropped to -40°F. During this winter they met Toussaint Charbonneau — a French-Canadian trapper living with the Hidatsa — and his wife Sacagawea, a Shoshone woman kidnapped from her tribe as a child.
The Corps hired Charbonneau specifically for Sacagawea's Shoshone language skills, which they needed to negotiate horses for the mountain crossing ahead. The decision would save the expedition.
Sacagawea gave birth to her first child in the cold of Fort Mandan, Lewis assisting the difficult delivery. The boy, Jean Baptiste Charbonneau, was nicknamed "Pomp" by Clark, who later took personal responsibility for his education.
Two months later, Pomp left Fort Mandan strapped to his mother's back and traveled the entire remaining journey to the Pacific and home — a 6,000-mile round trip before his first birthday. The youngest member of the Corps by roughly twenty years.
"Sah-cah-gah-wea our Indian woman was delivered of a fine boy… it is worthy of remark that this was the first child which this woman had boarn."
— Meriwether Lewis · February 11, 1805Lewis heard the roar before he saw it. The Great Falls of the Missouri — five cascades spanning 18 miles — were completely impassable by canoe. Native informants had described a portage of half a day. The reality was eighteen days of hauling boats over rocky terrain in blazing heat through prickly pear cactus that shredded their moccasins.
Lewis's specially designed iron-frame boat failed completely — the elk-hide covering split. They abandoned it and cut new canoes from cottonwood trees. The eighteen-day delay pushed the mountain crossing dangerously close to winter.
"I beheld those mountains with the most pleasureable sensation… the grandest sight I ever beheld."
— Meriwether Lewis · June 13, 1805Lewis had crossed the Continental Divide ahead of the main party and found a band of Shoshone. When Sacagawea arrived to translate, she recognized the chief: it was her brother, Cameahwait — she had been kidnapped as a child and hadn't seen her family in years.
The reunion transformed everything. Cameahwait provided 29 horses, a Shoshone guide named Old Toby, and detailed route information. Without this encounter — which Lewis called "a most affecting scene" — the Corps could not have obtained the horses needed to cross the Rockies before winter.
"She instantly jumped up, and ran and embraced him, throwing her blanket over him and crying profusely."
— Meriwether Lewis · August 17, 1805The Lolo Trail nearly ended everything. September snowstorms, temperatures below freezing, terrain so steep the horses fell. No game anywhere. The men ate their horses one by one, then boiled the tallow candles. Men who had survived a Sioux standoff and an 18-day portage were now stumbling in snow too weak to lift their packs.
Clark pushed ahead to find help. The Nez Perce fed the starving Corps and sent food back. The crossing took eleven brutal days. This — not the standoff, not the falls — was when the expedition most nearly failed.
"I have been wet and as cold in every part as I ever was in my life, indeed I was at one time fearfull my feet would freeze."
— William Clark · September 16, 1805Clark wrote five words, underlined three, misspelled one. It didn't matter. After 4,000 miles and eighteen months, the Corps of Discovery had reached the Pacific Ocean. Every man standing on that bank was the furthest west any U.S. citizen had ever documented standing.
The celebration was brief. They still had to survive a Pacific winter and make the 4,000-mile return home. But for that one rainy evening on the Oregon shore, they let themselves feel the full weight of what they had done.
"Ocian in view! O! the joy."
— William Clark · November 7, 1805Lewis and Clark put the winter camp location to a vote. Every member cast a ballot — including York, who was enslaved, and Sacagawea, a Native American woman. This vote happened 60+ years before the 15th Amendment and 115 years before women's suffrage.
Historians consider this one of the earliest documented instances of democratic inclusion in American history. Clark recorded Sacagawea's vote under the name "Janey." Her choice: a location near wapato root. It was counted alongside every other man's ballot.
It rained or was heavily foggy on all but 12 of their 106 days at Fort Clatsop. Fleas were relentless. Food was monotonous — elk and more elk, frequently spoiled. Nearly everyone suffered from respiratory illness and infections. And yet Lewis and Clark produced more scientific documentation that winter than at almost any other point in the journey.
The Corps arrived in St. Louis to crowds and cannon fire. Most of America had assumed they were dead. Lewis immediately sent a letter to Jefferson: they had done it. Each soldier received double pay and 320 acres of land. Charbonneau received $500.
York, who had paddled, carried, hunted, and voted alongside every other man for 28 months, received nothing — he remained enslaved. Sacagawea received nothing. Their contributions were acknowledged in words. Not in law.
"The party are all attached to their native homes and wish much to See their parents once more… they intend to return to the Illinois to pass the winter."
— Meriwether Lewis · September 23, 1806The People
Soldiers, frontiersmen, an interpreter, an enslaved man, and a Shoshone woman with her infant son.
Meriwether Lewis
1774–1809 · Age 29 at departure
Who He WasJefferson's personal secretary and a U.S. Army captain. Jefferson spent months training him in botany, celestial navigation, medicine, and natural science before departure. Intense, meticulous, brilliant — and prone to dark moods that worsened severely after the expedition ended.
His RoleThe expedition's primary scientist. He documented every new species with detailed descriptions and drawings, took astronomical readings to fix geographic position, managed diplomatic encounters, and wrote long, lyrical journal entries that remain among the finest nature writing in early American literature.
His ImportanceLewis's scientific journals became the foundation of western American natural history. He died in 1809 at age 35, likely by his own hand, before his journals were fully published. His pressed plant specimens are still preserved at Philadelphia's Academy of Natural Sciences — 220 years later.
Portrait: Charles Willson Peale, c. 1807 — Independence National Historical Park / Wikimedia Commons
William Clark
1770–1838 · Age 33 at departure
Who He WasA former Army officer and Lewis's close friend. Where Lewis was intense, Clark was steady. The men loved him. Native leaders respected him. A natural commander who kept the Corps functioning through the most brutal months — and a notoriously poor speller who mapped the continent with startling accuracy.
His RoleClark made the maps — 140 of them. Detailed charts of rivers, mountain passes, and geography that didn't exist anywhere before. He also managed day-to-day operations, discipline, and navigated the keelboat through currents that nearly capsized them multiple times.
His ImportanceClark's maps were the most immediately useful output of the expedition. Explorers, traders, and settlers used them for decades. After the journey, he served as Superintendent of Indian Affairs and Governor of Missouri Territory until his death at age 68.
Portrait: Charles Willson Peale, c. 1807–1808 — Independence National Historical Park / Wikimedia Commons
Sacagawea
c. 1788–1812 · Age ~16 at departure
Who She WasA Shoshone woman kidnapped by the Hidatsa as a child. The Corps hired Charbonneau specifically for her language skills — they needed a Shoshone interpreter. She joined the expedition while pregnant and traveled the entire journey with her infant son strapped to her back.
Her RoleHer practical contributions were enormous. She translated with the Shoshone, securing 29 horses for the Rockies crossing. She identified edible plants — camas root, wapato, bitterroot — that saved them from starvation multiple times. Her presence as a woman with a nursing infant served as a living peace signal at every tribe they encountered.
Her ImportanceWithout the horses she helped obtain from her brother, the Corps could not have crossed the Continental Divide. She received no compensation. Today she appears on the U.S. dollar coin — an acknowledgment, however late.
E.S. Paxson mural, Montana State Capitol / Wikimedia Commons
York
c. 1775–c. 1832 · Age ~29 at departure
Who He WasAn enslaved man owned by William Clark. He had grown up alongside Clark and participated fully in every aspect of the journey — from hunting to carrying loads through the mountains. He was large, powerful, and capable.
His RoleYork played a complete physical role in the expedition. His presence fascinated many Native peoples who had never seen a Black man, creating diplomatic openings the Corps used to advantage. At Fort Clatsop he voted in the democratic deliberation on where to build the winter camp — alongside free white men, as if he were equal. Legally, he was property.
His ImportanceYork served as a full Corps member, earned respect from Lewis, Clark, and Native peoples — then received nothing. No land. No pay. He remained enslaved for years after the journey. Clark eventually freed him around 1815. He is believed to have died of cholera around 1832. His story is the expedition's hardest truth.
John Ordway
1775–c. 1817 · Age ~29 at departure
Who He WasA New Hampshire-born Army sergeant — one of the most trusted non-commissioned officers. Reliable, disciplined, and literate. He wrote a journal entry without exception for every single day of the 28-month journey — the only Corps member to do so.
His Role & ImportanceOrdway frequently commanded independent detachments when the party split. Lewis purchased his journal for $300 — the only journal he bought from any Corps member — recognizing its completeness as irreplaceable. For the days when Lewis and Clark themselves wrote nothing, Ordway's entries are the only surviving record of what happened.
Seaman
Purchased August 1803 · $20
Who He WasLewis's large Newfoundland dog, bought in Pittsburgh for $20 — roughly $500 today. At roughly 150 pounds, Newfoundlands are built for cold water and loyalty. Seaman appears in over 40 journal entries, more than most humans on the expedition. Lewis clearly loved him.
Why He MattersSeaman retrieved shot game from rivers, warned the camp of approaching animals, and was once stolen — Lewis immediately dispatched three armed men to retrieve him. He represents something important: the expedition was a human journey. The men cared about their dog. That humanity is worth remembering alongside the science and diplomacy.
Discoveries
What they found — and why it mattered to a young nation trying to understand itself.
178 New Plant Species
Lewis documented 178 plant species unknown to Western science — the bitterroot (Montana's state flower, Lewisia rediviva), clarkia (named for Clark), Lewis's monkeyflower, ponderosa pine, and dozens of plants used medicinally by Native peoples. He collected physical specimens, pressed them, drew detailed illustrations, and wrote precise botanical descriptions for each one.
The largest single contribution to American botany in the 19th century. Lewis's pressed specimens are still held at Philadelphia's Academy of Natural Sciences. Source: Cutright, Lewis and Clark: Pioneering Naturalists.
122 New Animal Species
The Corps documented 122 animals new to science: the pronghorn antelope (fastest land animal in the Western Hemisphere), the grizzly bear, the prairie dog, the black-tailed deer, the western meadowlark, Clark's nutcracker, Lewis's woodpecker, and many more. Lewis sent a live prairie dog to Jefferson — it survived the months-long overland journey.
Several species still carry the names Lewis and Clark assigned. The grizzly encounters alone transformed American understanding of North American wildlife. Source: Cutright.
140 Accurate Maps
Clark produced 140 maps of the expedition's route — the most comprehensive cartographic survey of the American interior ever made. These charts accurately depicted the Missouri River system, the Rocky Mountains, the Columbia watershed, and the Pacific coastline. The 1810 compilation map became the definitive picture of the American West for a generation.
Clark's maps directly enabled the Oregon Trail and American settlement of the Pacific coast. Source: Allen, Passage Through the Garden.
The Northwest Passage Doesn't Exist
Jefferson's central hope was a short navigable river route directly connecting the Missouri to the Pacific. Lewis and Clark definitively proved this was impossible. The Rocky Mountains were not a single manageable ridge but a massive, multi-hundred-mile barrier. No water route could exist. This was a profound disappointment — and one of the expedition's most important findings.
Disproving the Northwest Passage myth forced American planners to design westward expansion around overland routes — and ultimately the transcontinental railroad. Source: Jackson, Thomas Jefferson & the Stony Mountains.
Contact with 50+ Nations
Lewis and Clark made formal contact with over 50 Native nations, recording their languages, customs, populations, and territorial boundaries. They distributed Jefferson Peace Medals, announced American sovereignty over the Louisiana Territory, and invited tribal leaders to Washington. Lewis's notes on Native languages were among the first records of many of these tongues.
The U.S. government's first serious effort to know the peoples of the West. This information shaped — and ultimately harmed — American-Native policy for generations. Source: Ronda, Lewis and Clark Among the Indians.
Millions of Words — The Journals
Lewis and Clark maintained extraordinarily detailed journals throughout — weather, geography, astronomy, plant and animal life, Native cultures, river depths. Together they run to millions of words across multiple volumes. Clark's entries track daily mileage with meticulous precision. Lewis's landscape descriptions are some of the finest nature writing in early American literature.
Published in 1814, the journals are a foundational scientific document. For ecologists studying pre-settlement western ecology, they remain irreplaceable. Source: Moulton, ed., Journals of the Lewis and Clark Expedition, 13 vols., Univ. of Nebraska Press.
Why These Discoveries Changed America
Before 1804, the American West was a blank space — unmapped, unstudied, heavily mythologized. The Louisiana Purchase gave the U.S. the land on paper; Lewis and Clark made it real. They replaced speculation with knowledge, blank spaces with rivers and mountain passes and named peoples and documented species.
The scientific discoveries proved the $15 million cost of the Louisiana Purchase was worth it many times over. The geographic knowledge enabled the fur trade, the Oregon Trail, and ultimately the settlement of the Pacific coast. And the expedition itself became a story — of two men, a baby, a dog, and thirty others who went into the unknown and came back with something that has lasted 220 years.