Two page ad from the October 31, 1936 issue of <i>Railway Age</i> marking the Mark Twain Zephyr's first year of service.  The ad also tells us that after entering service on October 27, 1935, the train was taken off its normal route on May 31, 1936 to serve the Chicago-Denver route as one of the Advance Zephyrs.  The Pioneer Zephyr also served as one of the Advance trains.  The Advance Zephyrs had no sleeping accomodations; the larger trains with them didn't arrive for the Denver-Chicago run until November of 1936.
Edward G. Budd Company, Philadelphia
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