Well, in the State of Florida if you do not insure your vehicle, your license is suspended. Getting pulled over with your license suspended could result in going to jail. If you do not register your vehicle (which requires proof of insurance) within 6 months of the date that the registration expired, they can pull you over, impound the car, fine you and throw you in jail.
You can have your license reinstated, but that still requires you to have insurance. Once you let your insurance lapse, rates go way up and some companies will not reinstate.