Do I need to remove my license plates when I sell or trade in my car?

It depends on your state. In some states plates stay with the owner and must be removed, transferred to your next car, or returned to the DMV; in others, plates stay with the vehicle. The dealer usually knows local rules for trade-ins. For private sales, check your state DMV website, since leaving plates on a car you no longer own could make you responsible for tolls or tickets.