Every state in the country has laws mandating auto insurance and how much must be purchased in order to legally drive on state roads. Ostensibly this insurance is for your own protection, though it doesn't really help much if you have an accident with a driver who is not obeying the state laws at all and doesn't have the minimum insurance to cover you. That possibility is why some states have, in addition to mandating liability insurance, also insist that you have uninsured/underinsured motorist protection as well. Uninsured/Underinsured insurance does what its name implies: it provides protection for your vehicle or medical insurance if you are involved in an accident with another driver who does not have insurance or does not have enough insurance to cover your expenses. With this type of insurance, you can generally rest assured that you will be cared for in an accident no matter what.
Fifteen years ago, it used to be a simple matter to get away with driving without insurance and praying you did not get into an accident and regret it. Now it is becoming increasingly difficult to do this, because insurance companies in many states are mandated by state law to notify the Department of Motor Vehicles if you let your insurance coverage lapse. The DMV will then send you notice that you have to provide proof of insurance within a certain time period or face consequences. This increased technology and communication between insurance companies and state agencies has lead to higher levels of compliance for insurance coverage.
If you choose to walk outside the law when it comes to driving without auto insurance, you are taking a great risk. Not only is there the risk of getting into an accident which, in most states, if you don't have insurance you will be found at fault for the accident no matter what happened because you legally shouldn't have been on the road to get involved in an accident in the first place, but you also run the risk of being sued personally for damages. In addition to those possibilities, you also run the high risk of running afoul of the law.
Different states have different laws and penalties for driving without insurance. Some are relatively mild, and some are downright draconian. Penalties for being caught driving without insurance range from a fine to having your license suspended. Your plates may be taken off of your vehicle, it might be impounded as well. If you continue to drive and are caught with a suspended license, you will be further fined and your license could be revoked entirely. Continue to violate the law and some states provide for jail or prison time beyond this level.