The AutoFarm GPS Steering Control System uses global positioning technology to automatically steer tractors and other machinery to tight tolerances (i.e., within 1-inch accuracy) even in adverse field conditions, such as dust and fog. A complete system consists of a cab box with touch-screen monitor, roof-top antenna, portable or fixed base station, and connecting cables. Available options include switch kits allowing transfer of the cab-box to other vehicles/machines, flash cards to transfer data between machines or from field to PC, and dataloggers for land mapping and surveying.