Systems for towing a trailer by a towing vehicle and a method for controlling such a system are disclosed. The systems and method are configured to maintain a constant towing load on the towing vehicle as well as optimizing other performance criteria such as fuel efficiency. The system comprises a closed loop controller, a towing arm assembly, a load measuring device, an electric hub motor, brakes, a motor controller and a brake controller disposed on the trailer. In another embodiment, two separate systems are installed, one on each side of the trailer. A load force feeds into a PID controller programmed with preset proportional, differential and integral parameters. The PID controller generates a command signal to either modulate the brakes or motor up or down depending on the sign of the command signal. A process output updates the system which continuously adjusts based on driving conditions.