16 Pa. Stat. § 5921
When a county road terminates at the corporate limits of a city or borough in the same or in another county and connects with a municipal street which the municipality has failed to properly improve, and the commissioners of the county in which the municipality is located deem the improvement of such municipal street necessary in order to make such county road easily accessible to the residents of the municipality or to the traveling public, the county commissioners may contract with the corporate officials of the municipality that such municipal street or any part thereof be improved, and also that there be improved, when necessary, and parts of the streets connected therewith which connect said county road with the business districts of said municipality or with a system of improved streets therein or which connect the said road with another county road terminating at the limits of said municipality. If several municipalities are contiguous to each other and at the corporate limits of any one of them a county road terminates and one or more of such municipalities have failed to properly improve any municipal street therein, and the county commissioners deem the improvement of such street necessary in order to make such county road easily accessible to the residents of the municipality or to the traveling public, the board of commissioners may enter into a similar contract with the corporate authorities of such municipality or municipalities.
16 P.S. § 5921