(All images: Wikimedia Commons, public domain)
In 1899, Illinois Telephone and Telegraph laid telephone cables through Chicago by building a network of underground tunnels. A narrow gauge railway was laid to assist with excavating the tunnels and installing the cables but the system was quickly adapted and used as a means for transporting freight between public stations, basements and elevator shafts.
The Illinois Telephone and Telegraph company had built the first 26 miles (42 km) of concrete tunnel by 1905, after which construction work became the responsibility of the Illinois Tunnel Company. Despite strike action in 1908, the company expanded the subterranean network to 60 miles (97 km) before the cost of construction left it bankrupt by 1909.
In 1912, the burden of the seemingly cursed network fell to the Chicago Tunnel Company who sold the communication installations and cables but continued to use the track to transport merchandise, coal and ash. The group was finally forced to abandon the unprofitable tunnels in 1959.
Interesting, the constant underground air temperature of 13 degrees Celsius (55 degrees Fahrenheit) led to a second line of business for the subterranean network – air conditioning. Several theatres above, all owned by the same company, purchased tunnel air to keep audiences cool. The same air was similarly used during winter, requiring less energy to heat than colder outdoor air.
Almost a century after construction, the doomed tunnels had helped facilitate the Chicago Flood of 1992, despite chief engineer George W. Jackson’s original intention that measures to prevent flooding be maintained through the use of portable bulkheads. The tunnels were ultimately drained at enormous expense. Chicago’s underground freight network was the main inspiration for London’s Post Office Railway (Mail Rail).