This Chicago subway cutaway image makes for a spectacular postcard. A description on the back of the postcard reads, “Shown are the main tubes; the downtown center platform, which is 3500 feet long; the two-way escalators to the mezzanines with store connections; and the State St. surface level. Features of the subway are ventilation, illumination, escalators, safety, comfort.” The level just below the street is part of the underground Pedway system that connects to various buildings, including department stores on State Street like the former Marshall Field’s building. The Pedway system is also great to use on days when the weather is bad. Postcard published by A.C. Company of New York. This postcard comes from the "white border" era of 1915 to 1930. The white border around the image allowed companies to save on ink costs. Some believe the quality of the images on postcards began to decline during this period.