From Consumer Wiki
The California Department of Motor Vehicles (DMV) requires licensure of mopeds and motorized bicycles. Special license plates are issued which must be displayed conspicuously by owners.
Department of Motor Vehicles
Special Processing Unit
PO Box 932345
Sacramento, CA 94232
The National Highway Traffic Safety Administration (NHTSA) establishes motor vehicle safety standards.
National Highway Traffic Safety Administration (NHTSA)
400 7th Street, SW
Washington, DC 20590
(Auto Safety Hotline)
(888) 327-4236 www.nhtsa.dot.gov