License plates are issued by a department of motor vehicles in the U.S. or in the case of the District of Columbia, the city government. The U.S. federal government issues plates for its vehicles and for those owned by foreign diplomats. Plates can contain symbols, colors, or slogans associated with the issuing jurisdiction. Small stickers are used to renew vehicle registration each year.
Here on LawServer you’ll find relevant state laws about license plates.