The national historic trails in the National Trails System of the United States are designated with the purpose of identifying and protecting historic routes and their artifacts for public use and enjoyment. In 1978, the Lewis and Clark National Historic Trail was established to commemorate the expedition of 1804–1806 through preservation of historical, cultural, and natural resources. We conducted a quantitative assessment of the condition and character of the landscape immediately surrounding the Trail. Specifically, we investigated the composition of land cover and status of vegetation condition, as well as the proportions of the trail passing through federal, state, and private ownership with various levels of conservation protections. We used a national index of “wildness” (i.e., ecological condition and impact of human development) to summarize landscape qualities and identify the wildest sections along the Trail. Much of the Trail has been altered through agricultural development and land use, but several areas remain relatively wild. Most of the Trail passes through land with no known conservation strategy and very little passes through wilderness or national parks. We did identify several areas where the Trail passes through existing federal land administered as “roadless” where permanent legislative protections could ensure the remaining wild and intact lands be preserved for future generations.