Certified mechanics can repair vehicles branded as salvage into a drivable condition.
This does not mean the vehicle can be operated on the road. Instead, drivable means the vehicle functions. The Department of Motor Vehicles will then inspect the work and, if the vehicle passes inspection, the DMV will issue a title. After this, vehicle can be insured and driven anywhere.
Note: Rebuilding regulations vary from state to state, so please refer to your local DMV for more information.