There are a few exceptions to this rule. In some states, it is possible to obtain a temporary registration permit, which will allow you to drive your vehicle for a limited period of time while you are in the process of registering it. In these cases, you may be able to obtain insurance coverage for your vehicle.
However, it is important to note that this is not always the case. Some insurance companies may still refuse to provide coverage for an unregistered vehicle, even if you have a temporary registration permit. Therefore, it is important to check with your insurance company to see if they will provide coverage for your unregistered vehicle before you purchase a policy.