The Appalachian Trail is the longest continuous footpath in the world. Its 2,140 miles run through 14 states--from Georgia to Maine--and vastly different natural and social environments, from the solitary splendor of mountain crags to the genial slopes frequented by dayhikers and scout packs. Each year, more than three million visitors enjoy the diverse scenery and cultures of the trail, united by a common appreciation for the outdoors. A lively and...