On April 13, 1992, freight tunnels running under the Loop were flooded with roughly 124 million gallons of water from the Chicago River, shutting down corporate and government buildings across the downtown area.
Electricity was immediately shut off, and buildings had to be evacuated, CBS Chicago reports. About 1,000 restaurants had to shut down immediately, wasting thousands of pounds of food, and most had to be reevaluated by health inspectors. Losses across the city totaled to an estimated $1.95 billion.
Most Chicagoans were surprised by the disaster, because many weren't aware of the network of defunct freight tunnels left under the city from the early 20th Century, writes WBEZ blogger John R. Schmidt. A crack in one of the tunnels caused by workers in 1991 was ultimately identified as the cause of the flooding.
As it had after so many notable hardships, Chicago quickly pulled itself back together. Revisit the 1992 disaster with archival photos of the flooding and its aftermath: