Economic Valuation of the National Park Service – Phase Reports (1A and 1B). Linda Bilmes, March 2015, Paper. "By measuring the net economic value of the National Park Service (NPS), this project will accomplish the first system-wide comprehensive assessment of the economic benefits the NPS provides the public. This valuation will include an estimate of the public’s (both visitors and non-visitors) willingness to pay for the units and programs of the National Park Service. In addition to the nationwide willingness to pay survey, detailed case studies are being developed for several specific areas..."