The Secretary is authorized, whenever in his opinion any portion of a State highway route within the limits of any State park or any park supervised, operated and maintained by a political subdivision or Federal resettlement project in the Commonwealth, shall be unnecessary for public use and travel, and has had presented to him a petition or request by the proper authorities of such State park or such park supervised, operated and maintained by a political subdivision or Federal resettlement project for abandonment of such portion of State highway as a State highway route, at any time by written order to declare such portion of State highway to be abandoned as a part of the system of State highways, and thereupon such portion shall no longer be a part of such system: Provided, That the Secretary shall first submit such proposed order of abandonment to the Governor and to the governing body of the political subdivision through which the highway passes and that the same shall be approved by them: And provided further, That the Secretary shall first give public notice of such proposed order of abandonment by advertising such proposed order of abandonment three times, each publication on a different day, in one newspaper of general circulation within the area adjacent to any such park or Federal resettlement project and by posting a copy of such proposed order of abandonment in a conspicuous place along such portion of State highway included in such order.