tag:digital.library.illinois.edu,2005:/itemsItems2023-11-30T16:47:51Ztag:digital.library.illinois.edu,2005:Item/392902016-08-11T15:00:05Z2023-11-30T16:47:51ZPost Office pneumatic tube systemCaption: "End of the big pneumatic tube system in the basement of the Chicago Post Office." From text: "The underground pneumatic tube system is the largest of the kind in the world. There are three double-tube trunk lines, aggregating over eighteen miles of eight-inch cast iron pipe. Of these lines the stockyards branch is the longest, the station being six and one-half miles away from the post-office, requiring thirteen miles of pipe. Relay stations on this line are at Twelfth and Twenty-second streets ... "University of Illinois at Urbana-Champaign Library