The problem of path tracking is critical to autonomous vehicle navigation. This problem has been approached using multiple feedback sensors that measure both the vehicle heading and position and also using cable guided systems measuring lateral error. This paper describes a path tracking controller that uses only the vehicle position as the single feedback value while providing a spatially similar response to disturbances independent of vehicle velocity. The results obtained on vehicles using this tracking controller are comparable to those obtained with systems measuring both vehicle position and heading. The controller has the additional benefits of being simple to implement, dealing effectively and predictably with system non-linearities, and providing a good measure of insensitivity to system variations. The controller described in this paper was developed for a two hundred horsepower farm tractor with Ackerman steering and has since been successfully used on a smaller tractor. The paper includes the derivation of the vehicle model, the development of the controller, and a discussion of system stability.