In some states such as Pennsylvania, a car owner can find his license plate number on the vehicle registration card or on the invitation to renew the vehicle's registration. If neither of these options are available, the owner should contact the local Department of Motor Vehicles.Know More
As of 2014 in Pennsylvania, the vehicle registration card includes the license plate number on the top left corner, underneath the expiration date. On the invitation to renew the vehicle's registration, the plate number is located along the top. In Pennsylvania, requests for duplicate license plates can be made on Form MV-44. If duplicate license plates are needed, vehicle owners should inquire with their specific state's DMV about the procedure for acquiring them.