This original postcard is from the 1934 Century Of Progress (Chicago World's Fair) which was held in Chicago. This vintage postcard is in excellent condition and features "Seventy Years of Progress In The Railway Post Office". The front features "The Old & The New Mail Cars Form A Part Of The Burlington Railroad Exhibit At A Century of Progress Exposition in 1934". The reverse side features a postcard format, which is unused and measures approx. 5 1/2" x 3 1/2".