16 Pa. Stat. § 5180
It shall be unlawful for any person to transport or cause to be transported any garbage over any public highway in the county in any vehicle unless such person has applied to and received from the county commissioners of the county, as in this act provided, a transportation license in respect of such vehicle. Such license shall be in the possession of the driver of such vehicle at all times when garbage is being transported therein and until such vehicle has been thoroughly flushed out and cleaned after transporting garbage, and shall be exhibited to any county or municipal police officer, county road caretaker, constable, deputy constable, or other peace officer, or officer invested with the powers of a peace officer, upon his request.
16 P.S. § 5180