You can learn more about the legislative history of the Appalachian Trail in the following works:

• Silas Chamberlain, On the Trail. A History of American Hiking (Yale University Press, 2016)
• Sara M. Gregg, Managing the Mountains. Land Use Planning, the New Deal, and the Creation of a Federal Landscape in Appalachia (Yale University Press, 2010)
• Sarah Mittlefehld, Tangled Roots. The Appalachian Trail and American Environmental Politics (University of Washington Press, 2013)
• Dennis Roth, "The National Forests and the Campaign for Wilderness Legislation" Journal of Forest History 28/3 (July 1984): 112-125