In every state, traffic laws make it unlawful to operate a motor vehicle when:

• The vehicle has never been registered with the state department of motor vehicles (or motor vehicles bureau) in the state where it is primarily used.
• The vehicle's once-valid registration has expired (i.e. required fees and filings were not submitted to the state motor vehicle department within the registration period).

In many states, penalties for driving a vehicle whose registration has expired will increase the longer the registration has lapsed. For example, if the vehicle's registration expired less than 6 months ago, the infraction might be considered a non-moving violation. But if the vehicle's registration expired more than 6 months ago, the offense may be considered a moving violation, which shows up as "points" on a driving record, and may lead to increased automobile insurance rates.

Traffic laws in most states differentiate between operating a vehicle that is not registered, and operating a vehicle without proof that the vehicle is registered (i.e. when a driver of a properly registered vehicle fails to carry a required registration certificate, or fails to display current registration stickers).

In most states, certain types of vehicles need not be registered -- including "off-highway" vehicles, stored vehicles, or vehicles for which a "non-operating" has been filed with the state department of motor vehicles.