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.
1200 New Jersey Avenue, SE West Building
Washington, DC 20590