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EnglishLewis and Clark Expedition: What It Was and Why It Still Matters
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The Lewis and Clark Expedition (1804–1806) was the first U.S. overland journey to the Pacific Coast and back, led by Meriwether Lewis and William Clark under the name Corps of Discovery. It matters today because it produced some of the earliest written and mapped records of the American West, and because the route it followed is now marked by interpretive sites, museums, and trail organizations you can visit. This explainer covers who was involved, where they went, what went wrong, and how to follow the trail yourself.
Who Lewis and Clark Were, and Why the Corps of Discovery Existed
Meriwether Lewis was an army captain and private secretary to President Thomas Jefferson. William Clark was a soldier and mapmaker who shared command of the journey. Jefferson commissioned the expedition to find a practical water route across the continent, study the land, and document its peoples, plants, and animals.
The group they led, the Corps of Discovery, was a military-style party of roughly three dozen people at its core, supplemented by interpreters, boatmen, and others who joined for parts of the trip.
Key Figures Beyond the Two Captains
The expedition is often remembered through a handful of people whose contributions shaped its survival and its story.
| Person | Role | Why they matter |
|---|---|---|
| Sacagawea | Shoshone interpreter and guide | Helped the party communicate with Shoshone bands and obtain horses for the Rocky Mountain crossing |
| York | Clark's enslaved valet | Took part in the full journey and was noted by several Indigenous groups the party met |
| Seaman | Newfoundland dog | Lewis's dog, frequently mentioned in the journals and a familiar figure on the trail today |
| John Colter | Hunter and scout | Later became one of the first known Euro-American explorers of the Yellowstone region |
The Route: St. Louis to the Pacific and Back
The journey ran in two broad halves.
Outbound (1804–1805)
- Departed from the St. Louis area in May 1804, moving up the Missouri River.
- Wintered at Fort Mandan in present-day North Dakota, where Sacagawea and her husband Toussaint Charbonneau joined.
- Crossed the Continental Divide, obtained horses from the Shoshone, and descended the Clearwater, Snake, and Columbia rivers.
- Reached the Pacific Coast in November 1805 and built Fort Clatsop for the winter.
Return (1806)
- Split into separate parties to explore different routes, then reunited.
- Returned to St. Louis in September 1806.
Major Challenges: The Great Falls Portage
One of the hardest stretches came in present-day Montana, where the party hit a series of waterfalls on the Missouri River. Rather than float through, they had to haul canoes and supplies overland around the falls — a slow, exhausting portage across rough ground in punishing heat.
That episode is why the Great Falls area remains a center of Lewis and Clark interpretation today. The Portage Route Chapter of the Lewis and Clark Trail Alliance, founded in 1983 and headquartered in Great Falls, Montana, is one of the oldest chapters of the national alliance and focuses on educating the public about the expedition and preserving the trail in that region.
How to Explore Trail Sites and Interpretive Centers Today
If you want to follow the story on the ground, the trail is organized through the Lewis and Clark Trail Alliance and its local chapters.
- Start with a chapter or the national alliance. The Portage Route Chapter's site includes a blog, partner links (including the Portage Route Chapter and the Lewis and Clark Honor Guard), and a Contact page for membership questions.
- Check for events. The alliance's 2026 Annual Meeting is scheduled for June 21–24 in Great Falls, hosted by the Portage Route Chapter — a concrete reason to plan a visit around that window.
- Use interpretive centers as anchors. The alliance's home office is headquartered in Great Falls at the Lewis and Clark Interpretive Center, which also houses the William P. Sherman Library and Archives.
- Look for field trips and tours. The chapter offers field trips and tours to sites along the trail and works to identify, develop, and maintain interpretive sites and signage.
Why It Still Matters
The expedition's journals and maps are among the founding documents of the American West, and the trail network built around them keeps that record accessible. Organizations like the Portage Route Chapter — a 501(c)(3) nonprofit and Montana nonprofit corporation — exist specifically to keep the story accurate and the sites preserved, which is what makes the trail something you can still visit rather than just read about.