Chicago dug 60 miles of freight tunnels under the Loop in 1899 and forgot them; in 1992, a damaged wall let the river in, and losses topped $1 billion

Under downtown Chicago lies a maze of old freight tunnels. Most people walking above them probably have no idea. In an essay for MAS Context, Chicago transit author Bruce G. Moffat writes that work on the tunnels began in late 1899 and that a tunnel wall collapsed in 1992, flooding the Loop. It is the story of a city that built an ambitious system and later neglected it.

A phone project with a secret

By around 1900, there was too much going on in the Loop. There were streetcars, delivery vehicles, and pedestrians competing for space everywhere. As Moffat says, there were six major railroad terminals in the area and a seemingly endless number of warehouses. At times, the streets were impassable.


The Illinois Telephone and Telegraph Company was one of the earliest providers of "long distance" telephone service. It was organized in 1898 to compete with the already established Chicago Telephone Company. The city needed it to put its wires underground. Construction was initiated in late 1899, and the conduits used were large compared to the wires they would use. Moffat's account notes they were as wide as seven and a half feet by six feet nine inches and able to accommodate a narrow gauge railway. Moffat adds that the company did not tell the city about the railroad until work was well along.

Life at 40 feet down

The company revealed in 1902 that it was constructing a railroad, and it got the nod through city ordinance the following year, says Moffat. The railroad was opened in 1906. Small cars were used for coal and ash and for store parcels. The company told regulators in 1910 it had nearly 60 miles of track. The system had 22 branch connections to railroad freight houses and 45 to commercial buildings. The trains were estimated to have kept the equivalent of 1.3 million vehicle trips off the streets.

Why the tunnels died out

The business didn't flourish in its time. The telephone end closed in 1916 due to huge losses, while the tunnel company was at best marginally profitable. In most cases, the owners themselves had to finance connection to their structures, and a truck at the curb was cheaper. Freight traffic was moved from the city center by railroads, the buildings switched from coal to gas, and the new subways cut off some department stores. According to the same essay, operations ended in 1959 and most locomotives and cars were sold for scrap. From the mid-1970s, the city started leasing out some of the sections for electrical and communication lines. Even then, maintenance was minimal.

A crack that had been there for months

In 1991, the city hired a contractor to drive wooden pilings into the riverbed to protect the Kinzie Street Bridge. One pile hit the tunnel wall. The essay also notes that no one noticed the damage until a survey crew working for a communications company spotted it in January 1992. Chicago Magazine explains that the work punctured clay between the river and the tunnel, allowing water and sediment to seep in. Then came April 13, 1992, and the wall broke. The river came rushing in, flooding the basements of many of the major buildings. Some areas of the Loop were evacuated because of fears that power outages could trap workers in high-rise buildings. The "Loop Flood" attracted worldwide attention.

The bill

Cost estimates differ. Some estimates put losses to business and property at over $1 billion. Chicago Magazine puts cleanup costs at nearly $2 billion. The magazine also reports that Loop activity was back to normal in about three days, but it took 19 more days to empty the tunnels. Crews sealed the gap with rocks, gravel, and concrete. Then they drilled shafts to let water drain into the Deep Tunnel system.

Who was at fault?

In the 1995 Supreme Court case Jerome B. Grubart, Inc. v. Great Lakes Dredge & Dock Co., victims of the flood sued, alleging that the company that operated the dock had weakened the tunnel while driving in piles. They also said the city hadn't taken care of it. These were claims, not findings. The court's opinion focused on whether the case was properly in federal admiralty court. The Chicago Magazine goes on to state that according to CBS, the city had knowledge of the leak before that time. Eight city officials lost their jobs, and it is not known if Mayor Richard M. Daley had any idea about the problem.

What’s left today

According to Moffat, there are some tunnels which are used to transport communications as well as high-voltage electric cables. There are other tunnels which are deserted, and some have been filled up or destroyed during the construction process. He argues that the tunnels are too narrow and deep to serve as a means of public transportation, and tours have not been encouraged in the city. He also notes the city made improvements after the flood to prevent a repeat.

Cities around the world probably have systems they built and later neglected. Chicago's story shows how hidden infrastructure can still require ongoing maintenance and how a crack that seems small today can turn into a very big problem later.