The Miniature Underground Train

A group of men ride on an electric locomotive in the tunnel. Published by V.O. Hammon Publishing Co. of Chicago.

Most children who spent a day at Kiddieland Amusement Park probably remember taking a ride on the miniature train. A similar tiny train once ran 40 feet under the ground in downtown Chicago. And the little tunnel is still there today.

Construction of the tunnel by the Chicago Tunnel Company began in 1899 and was inspired by a similar underground mail train system in London.

The purpose of the tunnel in Chicago, however, was for the installation of telephone and telegraph lines. The tiny trains eventually delivered coal, cargo and other items to buildings downtown and were later used to transport merchandise from department stores such as Sears Roebuck & Co. and Marshall Field’s.

Trains transport barrels in the underground tunnel. Published by V.O. Hammon Publishing Co. of Chicago. 

The company continued to expand the tunnel and began constructing railroad tracks for the miniature trains. The tunnel is 60 square miles long and runs under almost every street in the loop. The tunnel also takes the names of the streets above it. At one point, there were about 130 locomotives operating in the 7.5 ft-tall tunnel. The company also gave tours of the tunnel and people would sit in the tiny train cars, according to historians. 

The tunnel was in use until the late 1950s when the Chicago Tunnel Company went bankrupt. The tunnel was forgotten by most people until a 1992 underground flooding emergency.

Workers who were installing pillars in the Chicago River near the Kinzie Street Bridge damaged the tunnel and river water poured down into it. Workers were able to eventually seal up the puncture by dropping pieces of concrete into the river at the site. High-voltage electric cables and fiber optic cables now run through the tunnel.

Barrels and other items were shipped in the underground tunnel. Published by V.O. Hammon Publishing Co. of Chicago.