Lewis and Clark National Historic Trail

The Lewis and Clark National Historic Trail is a route across the United States commemorating the Lewis and Clark Expedition of 1804 to 1806. It is part of the National Trails System of the United States. It extends for some 4,900 miles (7,900 km) from Pittsburgh, Pennsylvania, to the mouth of the Columbia River near present-day Astoria, Oregon. It was originally established in 1978 as a 3,700-mile (6,000 km) trail following the historic outbound and inbound routes of the Lewis and Clark Expedition from Camp Dubois at Wood River, Illinois, to Oregon. In 2019, the trail was extended east to follow the expedition's 1803 preparatory journey from Pittsburgh to Wood River. The trail connects 16 states (Pennsylvania, Ohio, West Virginia, Kentucky, Indiana, Illinois, Missouri, Kansas, Nebraska, Iowa, South Dakota, North Dakota, Montana, Idaho, Washington, and Oregon) and many tribal lands.

The trail is administered by the National Park Service, but sites along the trail are managed by federal land management agencies, state, local, tribal, and private organizations. The trail is not a hiking trail, but provides opportunities for hiking, boating and horseback riding at many locations along the route. The trail is the continuously longest of the 30 National Scenic and National Historic Trails.

A highway driving route, marked as simply the Lewis and Clark Trail, follows along existing roadways and is also managed by state and local agencies.