Post Office - Clarks Mills 21 Lake Wilhelm Rd Clarks Mills, PA 16114 Phone : (724) 253-4040 Post Office - Clarks Mills Business Category Post Offices Toll-Free           (800) ASK-USPS United States Government--u S Postal Service, Clark Mills Ofc Clarks Mills, PA 16114 Phone : (724) 253-4040 United States Government--u S Postal Service, Clark Mills Ofc Business Category Government Offices-Federal Post Offices Government Offices & Public Schools