Meriwether Lewis and William Clark, along with their quasi-military companions who composed the Corps of Discovery, were the first white men to cross the western half of North America within the present limits of the United States.
Their exploration was the concluding act in the long and fruitless search for a watery route through the continent — the Northwest Passage — that had begun soon after Columbus discovered the New World.
Thomas Jefferson
The author of the 1803-1806 exploration was Thomas Jefferson, the third president of the United States. The expedition first occurred to him about the time the United States achieved independence in 1783.
During the presidencies of George Washington and John Adams, he twice tried unsuccessfully to have a transcontinental exploring party visit the vast area. On Jan. 18, 1803, Jefferson asked Congress for authorization and an appropriation of $2,500 to send a military expedition to explore along the Missouri River to its source in the Rocky Mountains and then down the nearest westward flowing stream to the Pacific Ocean.
Three reasons were given for the proposed mission: to expand the fur trade, to advance geographical knowledge and to explore the fauna and flora of the region.
When Jefferson sent his message to Congress, none of the territory he wanted to explore belonged to the United States. The land between the Mississippi River and the Rocky Mountains, called Louisiana, belonged to France; the Pacific Northwest was claimed by England, Russia, Spain and the United States.
On May 2, 1803, Louisiana became the territory. The journey to the Pacific Ocean would be strengthening the American claims to the region beyond the mountains.
President’s choice
To command the expedition, the president chose his private secretary, 6-foot, physically strong, but hot-tempered Capt. Meriwether Lewis. He, with the president’s concurrence, then selected a tall, large-boned, red-haired horseman and friend, William Clark, to be the expedition’s co-leader. It was a perfect union. Lewis would attend to the scientific work and negotiate with the Indians. Clark would marshal the men and look after the equipment.
After making initial preparations in the east, Lewis passed through Pittsburgh, floated down the Ohio River and made camp opposite the mouth of the Missouri River in Illinois. Clark and Lewis spent the winter of 1803-1804 recruiting and training the men, gathering supplies and collecting information about the Missouri River from traders and boatmen.
The permanent party included 37 young, unmarried soldiers, a half-breed hunter and interpreter and Clark’s slave, York. In addition, a corporal and five privates along with several French boatmen were to accompany the expedition during the first year and then return with records and scientific specimens.
Corps of Discovery
The Corps of Discovery began its historic journey on May 14, 1804. It started up the Missouri in a 55-foot keelboat and two pirogues averaging about 15 miles per day. By the end of October, the party had reached the Knife River and Mandan Indian territory near present-day Washburn, North Dakota. The contributions of these Indians and other tribes to the success of this adventure cannot be exaggerated.
With winter survived at Fort Mandan, the expedition resumed its journey April 7, 1805. Joining the group was another interpreter named Charbonneau and his Shoshoni wife along with her papoose called “Pompey.” Sacagawea was instrumental in purchasing horses necessary for the portage across the Rocky Mountains.
After crossing the mountains, the explorers descended the Clearwater, Snake and Columbia rivers to the Pacific Ocean, arriving in mid-November. After wintering on a river to be named after the two explorers, Lewis and Clark descended the Yellowstone River. Reuniting on the Missouri River, they reached St. Louis, Sept. 23, 1806.
The expedition accomplished its mission with remarkable success. During more than 28 months, it covered over 8,000 miles and cost about $40,000. It was the first giant step in opening the Trans-Mississippi West to the American people.
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