Driving without insurance for your vehicle is a serious offense in most all states unless you have some other form of financial responsibility on your vehicle. The category which being unable to show proof of auto insurance falls under will vary from state to state as do the penalties.
Some states might find this violation of the law to be only a minor or major traffic offense, making you obtain auto insurance and paying fines. Other states will impound your vehicle, suspend your license and registration or give you jail time. If you were in an accident while being uninsured, states can hand out even harsher penalties.
States such as Minnesota find driving without auto insurance to be a misdemeanor offense and subsequent violations of this law are considered to be gross misdemeanors. It is reported that Illinois has a new law that now makes driving without insurance a felony. In the future other states might follow their lead.
To find out what type of violation your state classifies driving without auto insurance to be, contact your local department of motor vehicles office.