Lewis and Clark expedition

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The nation's economy diversified and grew during the first decades of the United States' independence from the British Empire. With the vast majority of the population engaged in agriculture, Thomas Jefferson (18011809) believed that the health of the republic rested on small independent farms, owned by men he called "Yeoman farmers." Jefferson also favored a strong agrarian economy to counter tendencies of concentrating wealth and power in emerging manufacturing centers of the east.

To find more farming land, Jefferson looked West. Although the Mississippi River formed the western boundary of the United States, Jefferson wanted to explore the region beyond, fearing that if the U.S. did not expand westward, Britain or other countries might soon colonize the region. The lack of sufficient funding and political support, however, hindered such efforts through the 1790s.

In March of 1801 Jefferson became the third president of the United States (180109) and was in a position to further his exploration and land acquisition plans. By the time of his administration, Americans had a clearer understanding of the size of the continent they inhabited. In part, their knowledge was expanded because of the work of Captain James Cook (17281779), who measured the longitude along the Pacific Coast in 1780, and later of American Captain Robert Gray (17551806), who mapped the precise location of the Columbia River's mouth in 1792.

In 1801, however, Britain, Spain, France, and Russia still held vague claims to western North America, though the territory was in the possession of Native Americans. With water travel essential to commerce, Jefferson favored exploration and development of new water routes. The primary objective of a proposed expedition was, in Jefferson's own words, "to determine the most direct and practicable water communication across the continent, for the purposes of commerce."

Jefferson recruited Meriwether Lewis (17741809), a young army captain serving as Jefferson's personal White House secretary, to lead the expedition. Lewis, in turn, identified Lieutenant William Clark (17701838), an earlier commander of his, to serve as the expedition's co-leader. With agrarian interests in mind Jefferson directed them to make observations and measurements along the exploration route concerning plants, animals, soils, geography, and climate. Jefferson had Lewis tutored in Philadelphia by experts in these fields to prepare him for the expedition.

With preparations for the journey well under way Jefferson completed the Louisiana Purchase with Napoleon Bonaparte of France in 1803. The acquisition instantly doubled the size of the United States by adding 827,000 square miles of land and, most importantly, control of the Mississippi River for commerce. The expedition's purpose suddenly expanded to include exploration and evaluation of the new lands to determine their settlement and commercial potential.

The party of more than 40 men, called the Corps of Discovery by Jefferson, departed on May 14, 1804, from near the mouth of the Missouri River. Using large canoes and a keelboat for the first part of their journey (up the Missouri River), the party carried provisions to be supplemented along the way with wild game and fish. Lewis was in charge of scientific observations, with Clark directing map making and journal writing. In 1805 after spending their first winter at a Mandan Indian village on the Missouri in North Dakota, the expedition continued to the Missouri's headwaters and through the ranges of the Rocky Mountains. The expedition then journeyed down the Snake and Columbia rivers arriving at the Pacific Coast in the middle of November. They built Fort Clatsop just south of the Columbia River mouth and waited for a supply ship that never arrived. After a miserably wet winter, the expedition roughly retraced its route back eastward in 1806, splitting apart for much of the time to explore as much territory as possible. They arrived safely in St. Louis with great celebration on September 23 after exploring almost 8,000 miles of terrain in 863 days.

Two centuries later the Lewis and Clark Expedition remains remarkable for several reasons. Only one member of the party died, early in the journey, possibly from a ruptured appendix. By treating the Native Americans with respect, the party created a firm basis for trade, peace, and assistance with settlement. Though the expedition showed that the long-sought major waterway for trade did not exist, a wealth of biological, geographic, and cultural information was gathered in the party's eight-volume journal and maps. Included are previously unrecorded descriptions of 122 animals and 178 plants. The information vividly addressed the commercial potential of the newly acquired lands and territories west of the Rocky Mountains to the Pacific shore. Though the crossing was more difficult than anticipated, the Corps demonstrated its feasibility. The maps and detailed journal more immediately aided the U.S. fur trade. The fur trade spread across the region by the 1820s, and provided furs to a demanding European market.

Most importantly the expedition introduced the first United States presence west of the Rocky Mountains. Once the natural resources and potential settlement sites of the Northern Plains and Pacific Northwest were recorded, the agrarian economy envisioned by Jefferson could become a reality. U.S. citizens settled rich farmlands and established ports to ship produce to markets. As an integrated national economy was first emerging, Lewis and Clark opened the way to U.S. expansion from one coast to the other. The stage was set for an agricultural transformation of the west.

See also: Thomas Jefferson, Louisiana Purchase


Ambrose, Stephen E. Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West. New York: Simon & Schuster, 1996.

Botkin, Daniel B. Our Natural History: The Lessons of Lewis and Clark. New York: Putnam, 1995.

Moulton, Gary E., ed. The Journals of the Lewis and Clark Expedition. Lincoln, NB: University of Nebraska Press, 1983.

Nobles, Gregory H. American Frontiers: Cultural Encounters and Continental Conquest. New York: Hill & Wang, 1997.

Owsley, Frank L., Jr., and Gene A. Smith. Filibusters and Expansionists: Jeffersonian Manifest Destiny, 18001821. Tuscaloosa: University of Alabama Press, 1997.

Ronda, James P. Lewis and Clark Among the Indians. Lincoln: University of Nebraska Press, 1984.

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On 18 January 1803, President Thomas Jefferson delivered a secret message to both houses of Congress. "As the continuance of the act for establishing trading houses with the Indian tribes will be under the consideration of the Legislature," he advised, "I think it my duty to communicate the views which have guided me in the execution of that act." Jefferson complained that Indian tribes increasingly grew "uneasy at the constant dimunition of the territory they occupy" and that they refused "all further sale, on any conditions." To peaceably "counteract this policy of theirs," Jefferson wrote, "and to provide an extension of territory which the rapid increase of our numbers will call for, two measures are deemed expedient." First, he advised Congress to "encourage them [the Indians] to abandon hunting" and to take up the plow "and thereby prove to themselves that less land and labor will maintain them." Second, toward this end he urged Congress "to multiply trading houses among them, and place within their reach those things which will contribute more to their domestic comfort, than the possession of extensive, but uncultivated wilds." The government should operate these trading posts to "undersell private traders, foreign and domestic."

Later that year Jefferson revealed his full intentions when he instructed William Henry Harrison, territorial governor of Indiana, to "push our trading uses" upon the Indians, "because we observe that when these debts get beyond what the individuals [Indians] can pay, they become willing to lop them off by a cession of lands." In the secret message of January, Jefferson revealed even larger aims when he suggested this policy for "the river Missouri, and the Indians inhabiting it" since it afforded "a moderate climate, offering, according to the best accounts, a continued navigation from its source, and possibly with a single portage from the Western Ocean … to the Atlantic." He requested that twenty-five hundred dollars be appropriated "for the purpose of extending the external commerce of the United States" by sending a military expedition to "explore the whole line, even to the Western Ocean, have conferences with the natives on the subject of commercial intercourse, get admission among them for our traders … agree on convenient deposits for the interchange of articles, and return with the information acquired, in the course of two summers." This was all part of Jefferson's plan to make the United States into an "Empire of Liberty." Indians would be acculturated to white ways and together with whites would secure the property necessary for republican citizenship. He planned imperialism through absorption rather than colonization, ending in citizenship instead of subjection.

Three months after the January message, Jefferson shocked Congress with the Louisiana Purchase from France, doubling the size of the nation with the acquisition of the entire Missouri River watershed for pennies an acre. Indians could now "lop off their debts" by selling land in the territories between the Appalachian Mountains and the Mississippi River; then they would move to Louisiana, where government traders and missionaries would have the time to inure the natives to white ways and ideas while facilitating America's international commerce via a transcontinental water route.

Meanwhile, Jefferson's plan for an exploration party called the Corps of Discovery was already well under way. He had chosen his personal secretary, a fellow Virginian and veteran soldier Meriwether Lewis, to lead the expedition. Captain Lewis chose William Clark as his "co-Captain," and together they led more than thirty soldiers, a French interpreter and his teenage Shoshone wife, Sacagawea (a guide),

and Clark's black slave, York, in an expedition along the Missouri and Columbia Rivers to the Pacific and back between 1803 and 1806. They pursued Jefferson's instructions of 20 June 1803 to "explore the Missouri … for the purposes of commerce" while taking "observations of latitude & longitude, at all remarkable points on the river." They were to gather knowledge of all the Indian tribes along the way, as "the commerce which may be carried on with the people inhabiting the line you will pursue, renders a knowledge of those people important." Jefferson also instructed them to collect knowledge of the flora and fauna, to explore the Missouri's tributaries and the land they drained, to treat the natives "in the most friendly and conciliatory manner" to convince them to sign peace treaties with their enemies and with the United States, and finally to report on the feasibility of the fur trade at the Pacific. The president charged Lewis with recording all of this information in a journal to be published at the mission's conclusion.

The Corps of Discovery failed to find an all-water route to the Pacific. The explorers also failed at conciliatory diplomacy among the Indians. The Lakota never made peace with their Mandan or Arikara neighbors, and the U.S. Army would war with them for the rest of the century, eventually subjugating and herding them onto reservations. The Corps did succeed in coming home alive, with only one exception. It also brought back valuable maps; discovered new species of animals and plants, such as prairie dogs, the white-rumped shrike, and "prickly-pears"; and obtained valuable information about the richness of the land and Indian ethnography. But here too it actually failed. Lewis never published his journals. He committed suicide a few years after returning, and the journals remained unpublished and in unusable form for almost a century. This failed expedition cost the nation's taxpayers $38,722.25, more than fifteen times the original congressional allocation. The Corps of Discovery did succeed in capturing the imagination of the American people, who eagerly read reports in newspapers and awaited the explorers' return. They feted Lewis and Clark with balls and toasts in 1806 as trappers, traders, and settlers rushed up the Missouri River, settling the territory, clashing with Indians, and gradually dispossessing them of their hunting grounds and homes. Instead of using absorption methods, the U.S. Army and state militias conquered and colonized the West. For the Indians, the Lewis and Clark Expedition foreshadowed old-fashioned imperialism, not an "Empire of Liberty."

See alsoLouisiana Purchase; American Indian Policy, 1787–1830; American Indian Relations, 1763–1815; American Indian Removal; Presidency, The: Thomas Jefferson .


Ambrose, Stephen E. Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West. New York: Simon and Schuster, 1996.

Barth, Gunther, ed. The Lewis and Clark Expedition: Selections from the Journals, Arranged by Topic. Boston: Bedford, 1998.

DeVoto, Bernard, ed. The Journals of Lewis and Clark. Boston: Houghton Mifflin, 1997.

Ronda, James P. Lewis and Clark among the Indians. Lincoln: University of Nebraska Press, 1984.

Paul Douglas Newman

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Lewis and Clark Expedition

Meriwether Lewis (1774–1809) and William Clark (1770–1838) and their companions were the first white men to cross the western half of the present-day United States.

Jefferson's mission

On January 18, 1803, President Thomas Jefferson (1743–1826; served 1801–9) asked Congress for authorization and funding of $2,500 for an expedition to explore the Missouri River to its source in the Rocky Mountains, and then down the nearest westward-flowing stream to the Pacific. Jefferson gave two purposes for the proposed mission: to prepare the way for the extension of the American fur trade and to advance geographical knowledge of the continent. He particularly wanted to find the most direct water routes across the continent to support trade.

When he sent his message to Congress, none of the territory Jefferson wanted explored belonged to the United States. The area between the Mississippi River and the Rocky Mountains, called Louisiana , belonged to France, and the Pacific Northwest had been claimed by Great Britain, Spain, and Russia, as well as by the United States. But while he was planning the expedition, Jefferson was conducting a negotiation with the French government that resulted in the Louisiana Purchase of 1803. Under this agreement, the United States purchased a huge territory that more than doubled the nation's area. Part of the expedition, therefore, would be on U.S. soil, and part of it would be into areas the United States hoped to acquire.

To command the expedition, Jefferson chose his private secretary, Captain Meriwether Lewis. He, with the president's agreement, invited his old friend William Clark to be the expedition's coleader.

Organizing the corps

After making initial preparations in the East, Lewis traveled to Wood River, Illinois , opposite the mouth of the Missouri River. Clark and several recruits joined him on the way down the Ohio River. Lewis and Clark spent the winter of 1803–4 at Camp Wood River recruiting and training their men, gathering additional supplies and equipment, and collecting information about the Missouri from traders and boatmen. The final, permanent party included twenty-seven young, unmarried soldiers; a half-Indian hunter and interpreter named George Drouillard (c. 1775–1810); and Clark's black slave, York (c. 1770–1831). In addition, a corporal and five privates with several French boatmen were to accompany the expedition during the first season, and then return East with its records and scientific specimens. The expedition was called the Corps of Discovery.

Starting out

The Corps of Discovery began its historic journey on May 14, 1804. It started up the Missouri River in a 55-foot keelboat and two pirogues, or dugout canoes. Averaging about 15 miles a day, by the end of October the Corps of Discovery had reached the villages of the

Mandan and Minnetaree Indians near the mouth of the Knife River in present-day North Dakota . There the explorers built a log fort for winter quarters. During the long, cold winter at Fort Mandan, Lewis and Clark made copious notes in their journals, drew maps of their route, and sought the advice of numerous Indian visitors. From the Minnetarees, especially, they obtained valuable information about the course of the Missouri River and the country through which it ran. These and other Indians contributed enormously to the success of the exploration.

On April 7, 1805, the expedition resumed its journey. The party now numbered only thirty-three persons. It included, besides the permanent detachment, an interpreter named Toussaint Charbonneau (c. 1759–1840) and his young Shoshoni wife Sacagawea (c. 1786–1812). Sacagawea had been captured in an Indian raid and sold to Charbonneau. She was pregnant and gave birth to a baby boy during the journey. Later, Clark adopted the boy.

Uncharted territory

Passing through country never before visited by white men, by August 17 the expedition reached the navigable limits of the Missouri River. With Sacagawea's help, Lewis and Clark purchased horses from Indians who lived nearby and began the portage (getting across the land between two bodies of water with boats and equipment) of the Rocky Mountains. After crossing the mountains, the explorers descended the Clearwater, Snake, and Columbia Rivers to the Pacific, where they arrived in mid-November.

After wintering at Fort Clapsop (named for a neighboring tribe) on the banks of the present-day Lewis and Clark River on the south side of the Columbia River, the explorers started for home on March 23, 1806. They split up temporarily in present-day Montana . Lewis and a small party explored the Marias River, while Clark and the rest of the men descended the Yellowstone River. Reuniting below the mouth of the Yellowstone, they hurried on down the Missouri and arrived in St. Louis, Missouri, on September 23, 1806.

The Lewis and Clark expedition had accomplished its mission with remarkable success. In about twenty-eight months, it had covered more than 8,000 miles. During the entire journey, only one man lost his life, probably from a ruptured appendix. The explorers had met thousands of Native Americans in their travels but had only one violent encounter with them. The total expense of the undertaking was about $40,000. At this small cost, Lewis and Clark and their party took the first giant step in opening the land west of the Mississippi River to the American people.

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Lewis and Clark expedition, 1803–6, U.S. expedition that explored the territory of the Louisiana Purchase and the country beyond as far as the Pacific Ocean.


Thomas Jefferson had long considered the project of a western expedition, having encouraged John Ledyard when he proposed such an expedition in the 1780s, and as president he contemplated the matter in earnest and discussed it with his private secretary, Capt. Meriwether Lewis. When Congress approved the plan in 1803 and appropriated money for it, Jefferson named Lewis to head it, and Lewis selected William Clark as his associate in command. The purpose was to search out a land route to the Pacific, to strengthen American claims to Oregon territory, and to gather information about the indigenous inhabitants and the country of the Far West. Before the long march was begun, the Louisiana Purchase was made, increasing the need for a survey of the West.

The Expedition

The men were gathered and in the winter of 1803–4 were trained in Illinois across the Mississippi from St. Louis, the starting point. In May, 1804, they set out up the Missouri, and the next winter was spent at the Mandan villages (near present Bismarck, N.Dak.). In 1805 the hardest part of the journey was made. After reaching the Three Forks of the Missouri River (and naming the three branches after Jefferson, Madison, and Gallatin in loyalty to the administration), they followed the Jefferson as far as they could. Then their Shoshone guide, the remarkable woman Sacajawea, helped to obtain horses for them to continue across the high Rockies. They crossed the Continental Divide at Lemhi Pass and went over the Bitterroot Mts. through Lolo Pass. They had reached the land of westward-flowing rivers, and for part of their way they followed the Clearwater River down to the Snake River (long called the Lewis). The Snake took them to the Columbia River and they spent a miserable, rainy winter season in Fort Clatsop, a crude post they built on the Pacific coast.

In the spring they started back across the continent. In July, 1806, the party split for a time in order to explore as much territory as possible. Lewis went with a group down the Marias River, while Clark and most of the men descended the Yellowstone River; they were reunited on the Missouri at the mouth of the Yellowstone on Aug. 12, 1806. The party arrived in St. Louis on Sept. 23, 1806, and were greeted with much acclaim. The route of the expedition is commemorated by a series of sites along the Lewis and Clark National Historic Trail (see National Parks and Monuments, table).

The importance of the well-planned, well-executed expedition (only one person had been lost) was enormous. Although it was not the first transcontinental crossing in the north (Alexander Mackenzie had preceded them in a remarkable voyage), it opened vast new territories to the United States. Its influence on the history of the West is incalculable. Its results matched the efficiency and capability of its leaders.


Since the journey was under official auspices, many records were kept. The first report of it to be published appeared in a message of President Jefferson in 1806. In 1807 the journal of Patrick Gass appeared; it was several times reissued before The History of the Expedition under the Command of Captains Lewis and Clark was published (ed. by N. Biddle and P. Allen, 2 vol., 1814; repr. 1966). This appeared in later editions by E. Coues (4 vol., 1893; repr. 1965) and J. B. McMaster (1904). R. G. Thwaites edited a full issue of Original Journals of the Lewis and Clark Expedition (8 vol., 1904–5; repr. 2001; abridged ed. by B. DeVoto, 1953, repr. 1963) and G. E. Moulton edited a definitive edition of the journals of Lewis, Clark, and members of the Corps of Discovery published as The Journals of the Lewis and Clark Expedition (13 vol., 1983–2002, abridged ed. 2003).

There have been many studies and monographs on the expedition. See study by J. Bakeless (1947, repr. 1962). See also Letters of the Lewis and Clark Expedition (ed. by D. D. Jackson, 1962); R. H. Dillon, Meriwether Lewis: A Biography (1968); P. R. Cutright, Lewis and Clark, Pioneering Naturalists (1969); D. S. Lavender, The Way to the Western Sea (1988).

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LEWIS AND CLARK EXPEDITION. In 1803, President Thomas Jefferson purchased from France the extensive Louisiana Territory, a vast tract of land comprising nearly two-thirds of the present trans-Mississippi United States. Jefferson was a leading proponent of scientific expansion, a program of planned westward growth that called for the systematic exploration and mapping of new territory prior to settlement. Believing the Louisiana Territory held nearly unlimited potential for the future growth of the United States, Jefferson appointed his personal secretary, a twenty-nine-year-old army captain named Meriwether Lewis, as commander of an expedition to explore the vast region and to locate a water route to the Pacific Ocean. Lewis in turn chose Lieutenant William Clark, a thirty-three-year-old army officer and fellow Virginian, as his cocaptain. Late in 1803, Lewis and Clark established their headquarters at St. Louis, where they spent the winter gathering supplies and training the twenty-five soldiers under their command for the arduous journey.

The expedition set out for the unknown in the spring of 1804. Most of the first summer was spent making a difficult ascent up the Missouri River to present-day North Dakota, where the expedition wintered among the villages of the Mandan Sioux. When the expedition moved out the next spring, it was joined by the French-Canadian fur trader and interpreter Toussaint Charbonneau and his Shosone Indian wife, Sacagawea, who emerged as the party's principal guide. With Sacagawea in the lead, carrying her infant son much of the way, Lewis and Clark reached the headwaters of the Missouri and then pushed westward across the Bitterroot Mountains in Montana and Idaho late in the summer of 1805. That autumn the expedition crossed the Continental Divide and descended the Clearwater and Snake Rivers. On 7 November 1805, their canoes reached the mouth of the Columbia River, and the explorers at last laid eyes upon the Pacific Ocean. They built a small wooden post, Fort Clatsop, along the Columbia River as their winter headquarters and embarked upon the return voyage the following March. After recrossing the Rocky Mountains, Lewis and Clark divided the expedition into three groups to map more territory and reunited near the convergence of the Yellowstone and Missouri Rivers. Finally, after nearly twenty-eight months of exploration and travail, the weary expedition arrived to a hero's welcome at St. Louis on 23 September 1806.

In accordance with Jefferson's detailed instructions for the expedition, Lewis and Clark brought back a multitude of scientific information, including maps, the bones and hides from animal specimens, and caged birds and prairie dogs. Of the utmost value were their voluminous journals and diaries, which provided detailed firsthand descriptions

of the plant and animal life, geography, and Native peoples encountered during the journey. Although Lewis and Clark failed to locate a convenient water passage to the Pacific Ocean, they were nonetheless handsomely rewarded for their efforts. The U.S. government awarded both men 1,600 acres of land, while each member of the expedition received 320 acres and double pay. Lewis was later appointed governor of the Louisiana Territory, while Clark held a similar post in the Missouri Territory. Their most lasting achievement, however, was their contribution to the opening, both figurative and real, of the American West.


Ambrose, Stephen E. Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West. New York: Simon and Schuster, 1996.

Duncan, Dayton. Lewis and Clark: An Illustrated History. New York: Knopf, 1997.

Moulton, Gary E., ed. The Journals of the Lewis and Clark Expedition. 13 vols. Lincoln: University of Nebraska Press, 1983–2001.

Ronda, James P., ed. Voyages of Discovery: Essays on the Lewis and Clark Expedition. Helena: Montana Historical Society Press, 1998.

Daniel P.Barr

See alsoExplorations and Expeditions: U.S. ; Louisiana Purchase ; andvol. 9:Message on the Lewis and Clark Expedition ; The Journals of the Lewis and Clark Expedition .

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Lewis and Clark Expedition (1804–06).In 1803, Thomas Jefferson commissioned Capt. Meriwether Lewis and Lt. William Clark to explore what is now the northwest United States. The Louisiana Purchase later the same year altered the character of the planned expedition from an exploration of French territory to a first glimpse of lands that, in the view of many contemporaries, were essential to maintaining the agrarian, republican character of the nation.

The party of nearly thirty men—including Lewis and Clark, three sergeants, twenty‐two enlisted men, volunteers, interpreters, and Clark's slave—departed St. Louis in May 1804 heading up the Missouri River. They wintered at the present site of Bismarck, North Dakota, where they acquired a guide and translator, the Shoshone woman Sacagawea. In spring 1805, they continued to the headwaters of the Missouri River, struggled across the Continental Divide, and headed west along the Salmon, Snake, and Columbia Rivers to the Pacific. They returned to St. Louis the following year.

Their exploration revealed both the absence of a trans continental water route and a wealth of information, including detailed maps of their route, the earliest descriptions of Plains Indian culture, and observations of the environment. Until the development of the railroad and steamboat, however, the region they had explored remained a fur‐trapping ground and repository for removed Indians.
[See also Native Americans, U.S. Military Relations with.]


James P. Ronda , Lewis and Clark Among the Indians, 1984.
Stephen E. Ambrose , Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West, 1996.

James D. Drake

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Lewis and Clark Expedition (1804–06) US expedition to seek a route by water from the Mississippi to the Pacific Ocean. Instigated by President Thomas Jefferson, it was led by army officers Meriwether Lewis and William Clark, with the assistance of a Shoshone woman, Sacajawea. It reached the Pacific at the mouth of the Columbia River and produced valuable information about the country and peoples of the Northwest.