The Appalachian Trail, a thin ribbon of wilderness running through the densely populated eastern United States, offers a refuge from modern society and a place apart from human ideas and institutions. But as environmental historian--and thru-hiker--Sarah Mittlefehldt argues, the trail is also a conduit for community engagement and a model for public-private cooperation and environmental stewardship.

In Tangled Roots, Mittlefehldt tells the story of the trail's creation. The project was one of the first in which the National Park Service attempted to create public wilderness...