Sustainable Built Environments Senior Capstone Project / This paper examines the continued encroachment of Tucson, Arizona’s built environment on the borders of the surrounding protected lands. This will be a concern as the city of Tucson continues to grow and develop its rural areas. Case studies were conducted on three separate cities: Tucson, AZ, Estes Park, CO, and Missoula, MT. In each of the case studies the cities growth rate is looked at, as well as the zoning laws located around the boundaries of the cities respective protected lands. Tucson’s zoning laws and growth was compared to the other two case study cities. A sample buffer zone was created to show how these protected lands could help implement policies to maintain the ecosystems health, while also protecting Tucson’s rural population from dangerous encounters with wildlife or natural disasters.