On September 23, 1806, amid great public excitement, the expedition of William Clark and Meriwether Lewis returned to St. Louis, Missouri. They were the first to record an overland journey from the Mississippi River to the Pacific coast and back. Setting out in May 1804, they returned with extensive knowledge of the Louisiana Purchase territory.

In 1803, under President Jefferson, the United States purchased the Louisiana Territory for 3 cents per acre, totaling 828,000 square miles—one of the best land deals in history. Jefferson commissioned Lewis and Clark to explore this territory. The expedition, with about 48 men, traveled up the Missouri River in six canoes and two longboats, wintered in Dakota, and crossed into Montana, where they first saw the Rocky Mountains. They met the Shoshone Indians, who sold them horses, and journeyed through the Bitterroot Mountains, down the Clearwater and Snake rivers, reaching the Columbia River and the Pacific Ocean on November 8, 1805—the first European explorers to do so overland from the east. They wintered there before returning to St. Louis in spring.

Their journals recorded longitude, latitude, soil, climate, animals, plants, and native peoples, identifying new species like the grizzly bear and naming geographic locations after themselves, loved ones, friends, and their dog. Despite diseases and injuries, only one person died. Their expedition, one of the most consequential in U.S. history, helped establish U.S. territorial claims in Oregon.

Sources

Buckley and Jay H, “Lewis and Clark Expedition | Summary, History, Members, Facts, & Map,” Encyclopedia Britannica, last modified July 28, 2025, accessed September 9, 2025, https://www.britannica.com/event/Lewis-and-Clark-Expedition.

“Lewis and Clark Return to St. Louis | September 23, 1806 | HISTORY,” HISTORY, last modified May 28, 2025, accessed September 9, 2025, https://www.history.com/this-day-in-history/september-23/lewis-and-clark-return.

“Louisiana Purchase | Definition, Date, Cost, History, Map, States, Significance, & Facts,” Encyclopedia Britannica, last modified July 29, 2025, accessed September 9, 2025, https://www.britannica.com/event/Louisiana-Purchase.