67 Pa. Code § 212.7 – Signs and banners across or within the legal limits of a State-designated highway.

(a) Prohibition. It is unlawful to place any sign, marking or banner containing advertising matter of any kind on, across or within the right-of-way of any State-designated highway without the written consent of the Department.
(b) Abatement. A sign, marking or banner containing advertising matter placed without the written consent of the Department will be declared to be a public nuisance and may be removed by the Department with or without notice to the persons responsible for the placing of the sign, marking or banner containing advertising matter.