36 Pa. Stat. § 2718.102
The people of this Commonwealth would suffer economically if the Commonwealth failed to participate fully in the allocation and apportionment of Federal-aid highway funds since a reduction in such funds would necessitate increased taxation to support and maintain the Commonwealth's road program and system. Therefore, for the purpose of assuring the reasonable, orderly and effective display of outdoor advertising while remaining consistent with the national policy to protect the public investment in the interstate and primary systems; to promote the welfare, convenience and recreational value of public travel; and to preserve natural beauty, it is hereby declared to be in the public interest to control the erection and maintenance of outdoor advertising devices in areas adjacent to the interstate and primary systems within this Commonwealth.
36 P.S. § 2718.102