The Lewis and Clark Expedition (1804–1806) was the first overland expedition undertaken by the United States to the Pacific coast and back. The expedition team was headed by Meriwether Lewis and William Clark and assisted by Sacajawea and Toussaint Charbonneau. The expedition's goal was to gain an accurate sense of the resources being exchanged in the Louisiana Purchase. The expedition laid much of the groundwork for the Westward Expansion of the United States.
The Louisiana Purchase in 1803 sparked interest in expansion to the west coast. The United States did not know precisely what it was buying and France was unsure of how much land it was actually selling. A few weeks after the purchase, President Thomas Jefferson, an advocate of western expansion, had Congress appropriate $2,500 for an expedition. In a message to Congress, Jefferson wrote:
"The river Missouri, and Indians inhabiting it, are not as well known as rendered desirable by their connection with the Mississippi, and consequently with us.... An intelligent officer, with ten or twelve chosen men ... might explore the whole line, even to the Western Ocean..."[2]
Thomas Jefferson had long thought about such an expedition, but was concerned about the danger. While in France from 1785–1789, he had heard of numerous plans to better explore the Pacific Northwest. In 1785, Jefferson learned that King Louis XVI of France planned to send a mission there, reportedly as a mere scientific expedition. Jefferson found that doubtful, and evidence provided by John Paul Jones confirmed these doubts. In either event, the mission was destroyed by bad weather after leaving Botany Bay in 1788. In 1786 John Ledyard, who had sailed with Captain James Cook to the Pacific Northwest, told Jefferson that he planned to walk across Siberia, ride a Russian fur-trade vessel to cross the ocean, and then walk all the way to the American capital. Since Ledyard was an American, Jefferson hoped he would succeed. Ledyard had made it...