Driving without insurance is a serious offense in most areas. The penalty for this violation varies from state to state but can include large fines, license suspension or revocation, impounding of your vehicle (and payment of storage and towing charges incurred), community service or jail time. In some states, such as New Jersey, the mandatory penalties for a person found driving without insurance are even greater than those for a person receiving a DUI citation for the first time.
It is regulated by each state.
It is also likely you will have to comply with the state's financial responsibility laws by getting an SR22 or SR16.