16 Pa. Stat. § 5220
The board of county commissioners of the county is hereby empowered, in accordance with the conditions and procedure specified in the subsequent sections of this subdivision, by ordinance, to regulate in any portion or portions of such county which lie outside of cities, boroughs and townships of the first class the location, height, bulk and size of buildings and other structures, the percentage of lot which may be occupied, the size of yards, courts and other open spaces, the density and distribution of population, the uses of buildings and structures for trade, industry, residence, recreation, public activities or other purposes, and the uses of land for trade, industry, residence, recreation, agriculture, water supply, conservation, soil conservation, forestry, or other purposes.
16 P.S. § 5220