Centennial Parade R.P.O./1809-1909/Oct. 7, 1909/St. Louis, Mo. Large magenta oval cancel tying 1¢ Washington-Franklin on Centennial Expo. postcard, Very Fine. Estimate  $200 - 300. This is the first U.S. postal marking ever issued to celebrate a parade. Despite the R.P.O. designation the vehicle was actually a horse drawn Missouri Pacific mail coach on wagon wheels drawn by six white horses. The marking was used for one day only. $0 (Image)