Lewis and Clark Expedition - Overview


According to Jefferson himself, one goal was to find "the most direct & practicable water communication across this continent, for the purposes of commerce". Jefferson also placed special importance on declaring U.S. sovereignty over the Native Americans along the Missouri River, and getting an accurate sense of the resources in the recently completed Louisiana Purchase.

They were accompanied by a sixteen-year-old Shoshone Indian woman, Sacagawea, the wife of a French-Canadian fur trader. After crossing the Rocky Mountains, the expedition reached the Pacific Ocean in the area of present-day Oregon (which lay beyond the nation's new boundaries) in November 1805. They returned in 1806, bringing with them an immense amount of information about the region as well as numerous plant and animal specimens.

Reports about geography, plant and animal life, and Indian cultures filled their daily journals. Although Lewis and Clark failed to find a commercial route to Asia, they demonstrated the possibility of overland travel to the Pacific coast. They found Native Americans in the trans-Mississippi West accustomed to dealing with European traders and already connected to global markets. The success of their journey helped to strengthen the idea that United States territory was destined to reach all the way to the Pacific. Although the expedition did make notable achievements in science, scientific research itself was not the main goal behind the mission.

References to Lewis and Clark "scarcely appeared" in history books even during the United States Centennial in 1876 and the expedition was largely forgotten. Lewis and Clark began to gain new attention around the start of the 20th century. Both the 1904 Louisiana Purchase Exposition, in St. Louis, and the 1905 Lewis and Clark Centennial Exposition, in Portland, Oregon, showcased Lewis and Clark as American pioneers. However, the story remained a relatively shallow tale—a celebration of US conquest and personal adventures—until the mid-century, since which time the history has been more thoroughly researched and retold in many forms to a growing and appreciative audience.

In addition, a complete and reliable set of the expedition's journals was finally compiled by Gary E. Moulton. In the 2000s the bicentennial of the expedition further elevated popular interest in Lewis and Clark. Today, no US exploration party is more famous, and no American expedition leaders are more instantly recognizable by name.

Timeline of the Lewis and Clark Expedition

Lewis and Clark Expedition
Timeline: 1804–1806


  • May 14 – The Corps of Discovery departs from Camp Dubois at 4 P.M., marking the beginning of the voyage to the Pacific coast.
  • May 16 – The Corps of Discovery arrives at St. Charles, Missouri.
  • May 21 – Departure from St. Charles at 3:30pm.
  • May 24 – Pass Boones Settlement. Home of famous woodsman L.Willenborg.
  • May 25 – The expedition passes the small village of La Charrette on the Missouri River. Charles Floyd writes in his journal that this is "the last settlement of whites on this river."
  • June 1 – The expedition reaches the Osage River.
  • June 12 – Lewis and Clark meet three trappers in two pirogues. One of the men was Pierre Dorion-who knew George Rogers Clark. Lewis and Clark persuade Dorion to return to Sioux camp to act as interpreter.
  • June 26 – The expedition arrives at Kaw Point where the Kansas River drains into the Missouri River basin.
  • June 28–29 – First trial in new territory. Pvt. John Collins is on guard duty and breaks into the supplies and gets drunk. Collins invites Pvt. Hugh Hall to drink also. Collins receives 100 lashes, Hall receives 50 lashes.
  • July 4 – Marking Independence Day, the expedition names Independence Creek located near Atchison, Kansas.
  • July 11–12 – Second trial in new territory. Pvt. Alexander Hamilton Willard is on guard duty. Is charged with lying down and sleeping at his post whilst a sentinel. Punishable by death. He receives 100 lashes for four straight days.
  • July 21 – Reaches the Platte River, 640 miles from St Louis. Entering Sioux Territory.
  • August 1 – Captain William Clark's 34th birthday.
  • August 3 – The Corps of Discovery holds the first official council between representatives of the United States and the Oto and Missouri Indians at Council Bluffs, Iowa. They hand out peace medals, 15-star flags and other gifts, parade men and show off technology.
  • August 4 – Moses Reed said he was returning to a previous camp to retrieve a knife but he was actually returning to St. Louis (deserting).
  • August 18 – George Drouillard returns to camp with Reed and Otos' Chief Little Thief. Reed is sentenced to run the gauntlet (approximately 500 lashes) and is discharged from the permanent party.
  • August 18 – Captain Meriwether Lewis's 30th birthday.
  • August 20 – Sergeant Charles Floyd dies. He dies from Bilious Chorlick (ruptured appendix) He is the only member lost during the expedition.
  • August 23 – Pvt. Joseph Field kills first bison.
  • August 26 – Pvt. Patrick Gass is elected to Sergeant. First election in new territory west of Mississippi River. George Shannon is selected to get the horses back from Indians.
  • August 30 – A friendly council with the Yankton Sioux held. According to a legend, Lewis wraps a newborn baby in a United States flag and declares him "an American."
  • September 4 – Reach the mouth of the Niobrara River.
  • September 7 – The expedition drives a prairie dog out of its den (by pouring water into it) to send back to Jefferson.
  • September 14 – Hunters kill and describe prairie goat (antelope).
  • September 25–29 – A band of Lakota Sioux demand one of the boats as a toll for moving further upriver. Meet with Teton Sioux. Close order drill, air gun demo, gifts of medals, military coat, hats, tobacco. Hard to communicate language problems. Invite chiefs on board keelboat, give each 1/2 glass whiskey, acted drunk wanted more. Two armed confrontations with Sioux. Some of the chiefs sleep on boat, move up river to another village, meet in lodge, hold scalp dance.
  • October 8–11 – Pass Grand River home of the Arikara Indians 2,000+. Joseph Gravelins trader, lived with Arikara for 13 yrs. Pierre Antoine Tabeau lived in another village was from Quebec.
  • October 13 – Pvt. John Newman tried for insubordination (who was prompted by Reed) and received 75 lashes. Newman was discarded from the permanent party.
  • October 24 – Met their first Mandan Chief, Big White. Joseph Gravelins acted as interpreter.
  • October 24 – Expedition reaches the earth-log villages of the Mandans and the Hidatsas. The captains decide to build Fort Mandan across the river from the main village.
  • October 26 – Rene Jessaume lived with Mandan for More than 10 years, hired as Mandan interpreter. Hugh McCracken a trader with the North West Company. Francois-Antoine Larocque, Charles MacKenzie also visited L&C.
  • November–December – Constructed Fort Mandan.
  • November 2 –Hired Baptiste La Page to replace Newman.
  • November 4 – The captains meet Toussaint Charbonneau, a French-Canadian fur trapper living among the Hidatsas with his two Shoshone wives, Sacagawea and Little Otter.
  • December 24 – Fort Mandan is considered complete. Expedition moves in for the winter.


  • January 1 – The Corps of Discovery celebrates the New Year by "Two discharges of cannon and Musick-a fiddle, tambereen and a sounden horn."
  • February 9 – Thomas Howard scaled the fort wall and an Indian followed his example. "Setting a pernicious example to the savages" 50 lashes-only trial at Fort Mandan and last on expedition. Lashes remitted by Lewis.
  • February 11 – Sacagawea gives birth to Jean Baptiste Charbonneau, the youngest member of the expedition. Jean Baptiste is nicknamed "Pompy" by Clark. Lewis aided in the delivery of Sacagawea's baby, used rattle of rattlesnake to aid delivery.(Jessaume's idea).
  • April 7 to April 25 – Fort Mandan to Yellowstone River.
  • April 7 – The permanent party of the Corps of Discovery leaves Fort Mandan. The keelboat is sent down river. Left Fort Mandan in 6 canoes and 2 pirogues. Thomas Howard received a letter from his wife Natalia.
  • April 25 – Reached Yellowstone River Roche Jaune-sent Joseph Field up river to find Yellowstone. He saw Big Horn Sheep and brought back horns. Lewis searched area thought it would be a good area for fort. Future forts were built, Fort Union and Fort Buford.
  • May 14 – A sudden storm tips a pirogue (boat) and many items, such as supplies and the Corps' journals, spill over into the river. Sacagawea calmly recovers most of the items; Clark later credits her with quick thinking.
  • April 25 to June 3 – Yellowstone River to Marias River.
  • April 27 – Entered present day state of Montana.
  • May 5 – Lewis and a hunter killed first grizzly bear.
  • May 8 – Milk river. Called because of its milky white appearance. Natives called it "a river which scolds all others".
  • June 3 to June 20 – Marias River to the Great Falls.
  • June 3 – The mouth of the Marias River is reached. Camp Deposit is established. Cached blacksmith bellows and tools, bear skins, axes, auger, files, 2 kegs of parched corn, 2 kegs of pork, a keg of salt, chisels, tin cups, two rifles, beaver traps. 24 lb of powder in lead kegs in separate caches. Hid red pirogue. Indians did not tell them of this river. Unable to immediately determine which river is the Missouri, a scouting party is sent to explore each branch, North fork (Marias), South fork (Missouri). Sgt. Gass and 2 others go up south fork. Sgt. Pryor and 2 others go up north fork. Can't decide which river is Missouri. Clark, Gass, Shannon, York and Fields brothers go up south fork. Lewis, Drouillard, Shields, Windsor Pryor, Cruzatte, Lepage go up north fork. Most men in expedition believe north fork is the Missouri. Lewis and Clark believe south fork is Missouri and followed that fork.
  • June 13 – Scouting ahead of the expedition, Lewis and four companions sight the Great Falls of the Missouri River, confirming that they were heading in the right direction. Lewis writes when he discovers the Great Falls of the Missouri. "When my ears were saluted with the agreeable sound of a fall of water and advancing a little further I saw the spray arrise above the plain like a column of smoke.....began to make a roaring too tremendous to be mistaken for any cause short of the great falls of the Missouri."
  • June 14 – Lewis takes off on an exploratory walk of the north side of the river. Lewis shoots a bison. While he is watching the bison die, a grizzly bear sneaks up on him and chases him into river.
  • June 21 to July 2 – A portage of boats and equipment is made around the falls.
  • June 27 – cached- desk, books, specimens of plants and minerals, 2 kegs of pork, 1/2 keg of flour, 2 blunderbusses, 1/2 keg of fixed ammo.,and other small articles.
  • June – 18.4 miles Clark surveyed route. Clark was the first white man to see falls from south side of river. As Clark was surveying route he discovered a giant fountain (Giant Springs).
  • June 22 to July 9 – Construction of iron framed boat used to replace pirogues. It was floated on July 9 but leaked after a rain storm. The boat failed and was dismantled and cached July 10.
  • July 10 to July 15 – Established canoe camp to construct 2 new dugout canoes to replace failed iron frame boat.
  • July 15 to August 8 – Great Falls to the Shoshone Indians. Left canoe camp with 8 vessels traveled through the Gates of the Mountains, to the Three Forks (the 3 rivers that make up the Missouri River, The Jefferson River, The Gallatin River and the Madison River). The expedition is 2464.4 miles from mouth of the Missouri River. They pass Beaverhead Rock.
  • August 1 – Captain Clark's 35th birthday.
  • August 11 – Captain Lewis sights first Indian, since Ft. Mandan.
  • August 12 – Scouting separately from the main party, Lewis crosses the Continental Divide at Lemhi Pass.
  • August 13 – Lewis meets Cameahwait, leader of a band of Shoshone
  • August 15 to August 17 – Lewis returns across Lemhi Pass with Cameahwait and sets up Camp Fortunate.
  • August 17 – A council meets with the Shoshone, during which Sacagawea learns the fate of her family and reveals that Cameahwait is her brother. Lewis and Clark successfully negotiate for horses for passage over the Rocky Mountains. They buy 29 horses for packing or eating with uniforms, rifles, powder, balls, and a pistol. They also hire Shoshone guide Old Toby.
  • August 18 – Captain Lewis's 31st birthday. In his journal, he scolds himself for being "indolent," or lazy, and vows to spend the rest of his life helping people.
  • August 26 – Lewis and the main party cross the Continental Divide at Lemhi Pass. They thereby leave the newly purchased United States territory into disputed Oregon Country.
  • September 1 to October 6 – Crossing the Bitterroot Mountains.
  • September 4 – Meet Flathead Indians at Ross's Hole bought 13 more horses.
  • September 9 to September 11 - Camped at Traveler's Rest (Lolo, Montana), now a National Historic Landmark
  • September 13 – Crossed Lolo Trail starving, ate horses, candles, and portable soup.
  • October 6 to October 9 – Met Nez Perce Indians on Clearwater. Left horses, cached goods, built 5 dugout canoes for trip to ocean.
  • October 9 to December 7 – Traveled down Clearwater River, Snake River and Columbia River to ocean.
  • October 18 – Clark sees Mount Hood, which means they are now back in previously explored territory.
  • October 25 to October 28 – Camped at the Rock Fort, and first met the Chinookan-speaking people of the lower Columbia.
  • November 7 - Clark wrote in his journal, “Ocian in view! O! the joy.”
  • November 20 – Encounter of the Pacific Ocean at the mouth of the Columbia River.
  • November 24 – The Corps takes the matter of where to spend the winter to a vote. York, a slave, and Sacagawea, a woman, were allowed to vote. It was decided to camp on the south side of the Columbia River.
  • December 7 to March 23, 1806 – Fort Clatsop sewed 338 pairs of moccasins.
  • December 25 – Fort Clatsop, the Corps' winter residence, is completed.


  • January 1 – Discharged a volley of small arms to usher in the new year. Several Corps members build a salt-making cairn near present-day Seaside, Oregon.
  • March 22 – Corps of Discovery leave Fort Clatsop for the return voyage east.
  • March 23 to May 14 – Traveled to Camp Chopunnish.
  • April 11 – Lewis' dog was stolen by Indians and retrieved shortly. Lewis warned the chief that any other wrongdoing or mischievous acts would result in instant death.
  • May 14 to June 10 – Camp Chopunnish collected 65 horses. Prepared for crossing mountains. Bitterroot Mountains still covered in snow; cannot cross.
  • June 10 to June 30 – Traveled to Traveler's Rest (Lolo, Montana) via Lolo Creek. 300 miles shorter than westward journey. 17 horses and 5 Nez Perce guides.
  • June 30 to July 3 - Camped at Traveler's Rest (Lolo, Montana), now a National Historic Landmark
  • July 3 – The Corps of Discovery split into 2 groups with Lewis leading one group up the Blackfoot River and Clark leading another group up the Bitterroot River.
  • July 3 to July 28 – Lewis's party heads back to The Great Falls of the Missouri. Sgt. Gass, J. Thompson, H. McNeal, R. Field, R. Frazier, J. Fields, W. Werner, G. Drouillard, S. Goodrich.
  • July 7 – Lewis' group crosses the Continental Divide at Lewis and Clark Pass.
  • July 13 – Reached White Bear Island. Opened cache and many items were ruined. The iron frame of the boat had not suffered materially.
  • July 15 – Lewis explores Maria's river separates from Gass to meet at Mouth of Maria's between Aug 5 and no later than Sept 1. Maria's River expedition includes M. Lewis, R. Fields, J. Fields, G. Drouillard.
  • July 15 to July 26 – Camp Disappointment. Marias River does not go far enough north. Indians finally discovered.
  • July 20 – Sgt. Ordway's party (from Clark's party) meets Sgt. Gass's party at The Great Falls of the Missouri.
  • July 27 – The Blackfeet Indians try to steal Lewis's group's rifles. A fight broke out and two Indians were killed. This is the only hostile encounter with an Indian tribe.
  • July 28 – Lewis meets Ordway and Gass.
  • July 3 – Clark Explores Yellowstone-Leaves for Three Forks and Yellowstone. *Sgt. Pryor, *G. Gibson, *H. Hall, * R. Windsor. Sgt. Ordway, J. Colter, J. Colter, P. Cruzatte, F. LaBiche, T. Howard, J. Shields, B. LaPage, G. Shannon, J. Potts, W. Brattan, P. Wiser, P. Willard, J. Whitehouse, T. Charboneau, Sacagawea & Pomp, York.
  • July 6 – Clark's group crosses the Continental Divide at Gibbons Pass.
  • July 8 – Reached Camp Fortunate dug up cache from year before-tobacco most prized.
  • July 13 – Sgt. Ordway splits from Clark to travel up Missouri River to meet Lewis and Gass.
  • July 25 – Clark discovers and writes on Pompey's Pillar.
  • August 1 – Capt. Clark's 36th birthday.
  • August 3 – Clark arrives at confluence of Missouri and Yellowstone Rivers-moves down river because of mosquitoes.
  • August 8 – Pryor and party reached Clark. Pryor and party (*Sgt. Pryor,*G. Gibson, *H. Hall, *R. Windsor) left Clark with horses and a letter to Hugh Henry to get Sioux to go to Washington and make peace with other Indians. Horses stolen had to make bull boats to get across and down river.
  • August 11 – Lewis is accidentally shot by a member of his own party.
  • August 12 – The two groups rejoin on the Missouri River in present-day North Dakota.
  • August 18 – Capt. Lewis's 32nd birthday.
  • August 14 – Reached Mandan Village. Charbonneau and Sacagawea stayed . John Colter went back up river with trappers Hancock and Dickson provided rest of company stay with expedition all the way to St. Louis.
  • September 23 – The Corps arrives in St. Louis, ending their journey after two years, four months, and ten days.

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