16 Pa. Stat. § 5226
Such regulations shall be designated and enacted for the purpose of promoting the health, safety, morals, convenience, order, prosperity or welfare of the present and future inhabitants of the Commonwealth of Pennsylvania, including, among other things, the lessening of congestion in the streets or roads, or reducing the waste of excessive amounts of roads, securing safety from fire and other dangers, providing adequate light and air, preventing on the one hand excessive concentration of population and on the other hand excessive and wasteful scattering of population or settlement, promoting such distribution of population and such classification of land uses and distribution of land development and utilization as will tend to facilitate and conserve adequate provisions for transportation, water flowage, water supply, drainage, sanitation, educational opportunities, recreation, soil fertility, food supply, protection of the tax base, securing economy in governmental expenditures, fostering the Commonwealth's agricultural and other industries, and the protection of both urban and non-urban development.
16 P.S. § 5226