Systems and methods are described for monitoring movement of a trailer relative to the towing vehicle and providing driver-assistance information to the driver of the towing vehicle. The system determines a velocity vector for the host vehicle at a location near a rear of the host vehicle at a defined lateral distance from a trailer hitch installed on the host vehicle. The system also determines a velocity vector for the trailer at a corresponding location on the trailer—that is a location on the front of the trailer at approximately the same defined lateral distance from the trailer hitch. The system compares the velocity vector for the host vehicle to the velocity vector for the trailer and determines, based on the comparison, whether a jack-knife condition is likely to occur. If a jack-knife condition is likely to occur, the system generates a warning signal.