 The state adopted a 15-inch diamond, black-on-white text with the image of a covered wagon occupying the top half and the route number on the bottom half, a design created by State Engineer Robert L. Cochran.The oxen-and-wagon symbol later became the official state symbol of Nebraska.The modern version of the route markers are rectangular with a white trapezoidal field set on a black background with the state name, route number and covered wagon design in black.