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Exploration and Settlement

Lewis and Clark

What was the goal of the Lewis and Clark expedition?

The expedition, which began in 1804 and took more than two years to complete, had three purposes: to chart a route that would be part of a passage between the Atlantic and Pacific Oceans; to trace the boundaries of the territory obtained in the Louisiana Purchase; and to lay claim to the Oregon Territory.

Thomas Jefferson (1743–1826) was president of the United States at the time, and he believed that a route could be found between St. Louis and the West Coast. As early as 1801, Jefferson had conceived of the idea that the Missouri and Columbia Rivers might be followed west, leading to the Pacific. The journey would also be a reconnaissance mission; information would be collected about the vast region and communications would be set up with its inhabitants. On April 30, 1803, the United States bought the Louisiana Territory from France. The purchase extended from the Mississippi River in the east to the Rocky Mountains in the west, and from the Gulf of Mexico in the south to British America (Canada) in the north. Jefferson soon picked his private secretary, Virginia-born Meriwether Lewis (1774–1809), to lead the westward expedition. Lewis then chose as his co-leader William Clark (1770–1838), who, as a lieutenant in the U.S. Army, had served General Anthony Wayne on the frontier (1792–96). Beginning in the summer of 1803, Lewis and Clark undertook the necessary preparations for the overland journey. These included studying the classification of plants and animals, learning how to determine geographical position by observing the stars, and recruiting qualified men (mostly hunters and soldiers) for the expedition.

On May 14, 1804, the Lewis and Clark expedition left St. Louis and headed up the Missouri River to its source. They then crossed the Great Divide and followed the Columbia River to its mouth (in present-day Oregon) at the Pacific Ocean, where they arrived in November 1805—one and a half years after they had set out. They arrived back in St. Louis on September 23, 1806, having gathered valuable information on natural features of the country, including its flora, fauna, and the Indian tribes who lived there.

The expedition had been helped by the addition, in what is now North Dakota, of a Shoshone Indian woman named Sacagawea (c. 1786–1812). Lewis and Clark had hired her husband, French-Canadian trader Toussaint Charbonneau, as an interpreter during the winter of 1804–05. Lewis and Clark thought that Sacagawea would be able to help them communicate with the Shoshone living in the Rocky Mountains, which she later did: Her brother was their chief.

After the expedition, Lewis was made governor of Louisiana Territory, a post he served from 1807 to 1809. Clark resigned from the army in 1807 and became brigadier general of the militia and superintendent of Indian affairs for Louisiana Territory. In 1813 he became governor of the Missouri Territory (the Louisiana Territory less the state of Louisiana, which was organized as a state admitted into the Union in 1812), a post he held until 1821.



Lewis and Clark, who headed an early nineteenth-century expedition to explore the western United States, address members of an Indian tribe. (Illustration by Patrick Glass.)
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