Lewis and Clark expedition
Meriwether Lewis and William Clark

May 1804 - September 1806

Lewis and Clark expedition was an early exploration of the vast wilderness of what is now the Northwestern United States. The expedition was sponsored by the U.S. government and led by U.S. Army officers Meriwether Lewis and William Clark. The expedition began near St. Louis, Mo., in May 1804 and returned to that city in September 1806.

Lewis and Clark traveled a total of about 8,000 miles on the expedition. Starting from a camp near St. Louis, they journeyed up the Missouri River, across the Rocky Mountains, and along the Columbia and other rivers to the Pacific coast. They returned to St. Louis with maps of their route and the surrounding regions; specimens and descriptions of plant, animal, and mineral resources; and information about the native peoples of the West. The success of the expedition enabled the United States to claim the Oregon region, which included what are now the states of Oregon, Washington, and Idaho.

Soon after Thomas Jefferson became U.S. President in 1801, he began to plan an expedition to chart a route through the Louisiana Territory and the Oregon region. He believed that a route to the Pacific coast along the Missouri and Columbia rivers could be part of a land-and-water passage between the Atlantic and Pacific oceans. The President's plan included gathering scientific information about the regions and establishing communication with the Indians who lived in them. After the United States bought the Louisiana Territory from France in 1803, the expedition received the additional tasks of tracing the boundaries of the territory and laying U.S. claims to the Oregon region.

Jefferson chose Meriwether Lewis to lead the expedition. Lewis was a U.S. Army captain and Jefferson's private secretary. Lewis, in turn, selected William Clark, a former U.S. Army officer, to join him. Lewis had served under Clark in the Army. Clark had resigned from the Army in 1796 but reenlisted in 1803 to join the expedition. When he reenlisted, he received the rank of lieutenant, which was below that of Lewis. But the two men privately agreed to lead the expedition jointly, and on the expedition Clark was always addressed as captain. Both men had wilderness experience and had served in Army campaigns against Indians. In addition, Clark had considerable mapmaking skills, and Lewis had some training in the study of animals and plants.

During the summer of 1803, Lewis spent time studying in Philadelphia. He learned how to classify plants and animals and how to determine geographical position by observing the stars. He then went to Pittsburgh, Pa., and, in late August, left the city in a large flat-bottomed boat called a keelboat. Near Louisville, Ky., he was joined by Clark, who had been recruiting men from nearby Army posts. For the expedition, the explorers chose skilled woodsmen and hunters who were accustomed to manual labor and military discipline. Most of the men were soldiers.

In December 1803, the party established winter quarters at Camp Dubois (Camp Wood), across the Mississippi River from St. Louis. At the camp, Lewis and Clark trained their men and learned from fur traders and travelers about the regions the party would explore.

On May 14, 1804, the expedition set out from Camp Dubois in the keelboat and two pirogues (dugout canoes). At first, the expedition consisted of about 50 men. Many were French boatmen temporarily hired to move the heavy keelboat and other craft against the Missouri's swift current. The men moved the keelboat by pushing poles against the river bottom or by pulling the boat with ropes from shore. The keelboat carried a large amount of supplies, including food, medicine, scientific instruments, weapons, and presents for the Indians.

As Lewis and Clark traveled up the Missouri, they were amazed at the beauty of the land and its abundant wildlife. In September, the explorers had a tense encounter with Sioux Indians. After the explorers had talked and exchanged gifts with them, the Sioux refused to allow Clark to return to the boat. The Indians let him go only after they saw that the soldiers in the party were preparing to fight. Other meetings with Indians were friendly. Often, Indians helped the men by describing the way ahead and by providing food.

In October, the expedition reached the villages of the Mandan and Hidatsa Indians in what is now North Dakota. The group established its winter camp, Fort Mandan, near the villages. During the winter, a French-Canadian trader named Toussaint Charbonneau and his wife, Sacagawea, a Shoshone Indian, joined the expedition. Sacagawea became an interpreter. At the winter camp, Lewis and Clark brought their diaries and maps up to date and wrote about the Indians.

The journey resumed on April 7, 1805. The party that continued west consisted of 33 people. They traveled in the two pirogues and six newly built canoes. The others returned to St. Louis with the keelboat, which was loaded with animal, plant, and mineral specimens; maps; and reports for Jefferson.

As Lewis and Clark traveled west into what is now Montana, the terrain became increasingly dry, treeless, and rugged. In early June, the party spent nearly a week where the Marias River joins the Missouri, trying to decide which of the two streams was the main river. The explorers made the right choice and soon afterward arrived at the Great Falls of the Missouri. They skirted the falls with much difficulty, having to carry the boats and supplies overland for 18 miles.

As they approached the mountains, the explorers hoped to meet friendly Indians who would provide horses and information to guide the party through the region. Luckily, in mid-August, they met a band of Shoshone Indians whose chief was Sacagawea's brother. The explorers traded for horses and supplies, obtained an Indian guide, and began their passage through the Bitterroot Mountain Range. This range rises along what is now the Idaho-Montana border.

Crossing the mountains in Idaho was the most difficult part of the journey up to that time. The explorers had to lead their horses along rocky, narrow mountain paths. Some horses lost their footing and fell to their death, and precious supplies and equipment were lost. As winter set in, there were fewer and fewer wild animals to kill for food. The explorers went hungry until they finally killed and ate some of their pack horses.

As the explorers came out of the mountains, they met the helpful Nez Perce Indians and traded for fresh supplies. Near the present-day Idaho-Washington border, the explorers built canoes, which they used in traveling down the Clearwater, Snake, and Columbia rivers. On the rivers, they faced treacherous falls and rapids and met new Indian peoples. In November 1805, the explorers reached the Pacific coast. They built Fort Clatsop near present-day Astoria, Ore. They spent the winter at the fort and prepared for their return to St. Louis.

The homeward journey began on March 23, 1806. Lewis and Clark decided to split the expedition into two groups on part of the return trip. Lewis would lead one group over a new, shorter route through the mountains, and Clark and the other group would explore the Yellowstone River. The expedition reached the ridge of the Bitterroot Range in June and then divided into the two groups at a spot the explorers called Traveler's Rest. Lewis and his group reached the Missouri River by the new, shorter route and then set out to examine the Marias River. Along the Marias, Lewis' party had a brief fight with some Blackfeet Indians who tried to steal their guns and horses. The explorers escaped unharmed, but two Indians were killed. Clark's group reached the Yellowstone River by a new route. At the Yellowstone, they built canoes and followed the river to its junction with the Missouri. In August, the two groups reunited on the Missouri, below the mouth of the Yellowstone. They then returned to St. Louis, arriving on Sept. 23, 1806, to the welcoming cheers of the city's people.

The most important result of the expedition was that it enabled the United States to claim the Oregon region. This claim helped make possible the great pioneer movement that settled the West in the mid-1800's. The explorers also established peaceful contact with most of the Indian tribes they met. They collected a variety of Indian goods and gathered information on Indian languages and culture.

Lewis and Clark's journals of the expedition describe the natural resources and native peoples of the West and contain information on many scientific matters. They were first published in an edited version in 1814 and in their entirety in 1905.

Contributor: Gary E. Moulton, Ph.D., Prof. of History, Univ. of Nebraska, Lincoln.

Additional resources

The Journals of the Lewis and Clark Expedition. Ed. by Gary E. Moulton. Univ. of Nebraska Pr., 1983-. Multivolume work, publication in progress.

Moulton, Gary E. Lewis and Clark and the Route to the Pacific. Chelsea Hse., 1991. For younger readers.


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