• photo of a replica keelboat with a crew member on the bow at sunset

    Lewis & Clark

    National Historic Trail ID,IL,IA,KS,MO,MT,NE,ND,OR,SD,WA

Environmental Factors

scenic view of mountains looking west from Rt. 275 between Three Forks and Helena, near Townsend, Montana

Looking west from Montana Rt. 275 between Three Forks and Helena, near Townsend, Montana.

NPS JH-Anderson

Many environmental factors exist along the Lewis and Clark National Historic Trail. Everything from non-native species to untimely releases of water from dams, to the loss of habitats, can have significant impacts to this historic corridor.




Learn about some of these factors by visiting sites along the trail highlighted in the right-hand column.

Did You Know?

Columbia River

Jefferson sent the Corps of Discovery to find the "most direct & practicable water communication across [the] continent." Although the Corps did not find the water route Jefferson had hoped for, they did explore 4 major rivers: the Missouri, the Columbia, the Snake, and the Yellowstone.