Born in Virginia in 1774, Meriwether Lewis developed a love of the wilderness and became an expert hunter as a child. He served in the militia during the Whiskey Rebellion of 1794 in western Pennsylvania and later transferred into the regular army.

In 1801 Lewis became private secretary to President Thomas Jefferson, who for the next two years unofficially prepared Lewis for leadership of a transcontinental exploring expedition. Fellow Virginian William Clark was appointed at the request of Lewis to share his command. When the United States purchased the Louisiana Territory in 1803, Congress appropriated $2,500 for its exploration. To further prepare for the expedition before leaving, Lewis studied botany, zoology, and celestial navigation in Philadelphia.

The three-year expedition, from St. Louis to the Pacific Ocean at the Oregon Coast and back, succeeded not only because of the party's skills but also because its two leaders worked together in such close harmony. The party spent a long and wet winter in the general vicinity of the mouth of the Columbia River in Oregon before returning east. Following Jefferson's instructions, Lewis and his colleagues kept a detailed journal of the trip, thus contributing a priceless narrative of North American exploration. These diaries helped dispel ignorance about the region and did much to open the way for westward expansion.

Lewis and Clark each received 1,600 acres of public land as a reward for their efforts. On his resignation from the army Lewis was named governor of Louisiana Territory in 1808. He died under mysterious circumstances at an inn on the Natchez Trace while en route to Washington. The controversy about whether his death resulted from murder or suicide continues.

Commemorating the bicentennial of the 1804-1806 expedition, celebrations began in 2004 in cities and historic sites along the Corps of Discovery's route.