Commemorative postal covers for the first run and millionth mile of the "Pioneer Zephyr". These covers were carried aboard the train on November 11, 1934 (first run) and December 29 1939 (millionth mile). The graphic was applied by the Chicago, Burlington and Quincy Railroad to commemorate the events. The lower cover for the millionth mile commemoration also shows an example of a perfin stamp, with the letters "CBQ", the reporting mark of the Chicago, Burlington and Quincy Railroad, perforated into the stamp itself.