Twenty years ago today, Chicagoans got an unexpected history lesson. April 13, 1992 -- the day of the flood.
Early in the 20th Century, a network of tunnels was built 40 feet below the streets of downtown
Chicago. The tunnels were used mostly for hauling freight between Loop buildings. They were abandoned during the 1950s.
By 1991 most Chicagoans knew nothing about the freight tunnels. That December, a contractor happened to be sinking wooden pilings into the river at the Kinzie Street Bridge. The work caused a crack in one of the tunnel walls. The city was notified about the accident.