RSA 266:64: Tow Bars Required.

Except for duly registered wrecking vehicles and transporters or motor vehicles towing with a chain or cable for no more than one mile another motor vehicle which is disabled and unable to proceed under its own power, no motor vehicle shall be used to tow another motor vehicle upon any way unless the 2 vehicles shall be connected by a tow bar of sufficient strength to control the movement of the vehicle being towed without manual steering of said towed vehicle.