An automatic guidance system and method are provided for a gantry crane to permit accurate tracking along a path, including a curved path. The position of the crane is determined from two spaced apart GPS receivers fixed to the crane. A guidance controller determines a plurality of error measurements from respective front, center and rear points of the crane relative to a current tracking line, which is a line tangent to the path at a current position of crane. In an embodiment, the system includes a base station that can be used to transmit data to the crane to specify a particular destination location of the drive path, or to transmit data representing the drive path itself.