CHICAGO -- State officials are seeking the public's help to find old maps of long-closed underground coal mines.
The maps help determine whether an area is a risk of subsidence -- holes or sagging that can damage homes and other buildings, like a southern Illinois school that had to be rebuilt five years ago.
But Department of Natural Resources mine experts say they only have about 2,000 maps for more than 4,000 mines that operated in the state over the past 160 years.
They want to make digital copies before they deteriorate or are destroyed, and believe many are in private hands.
Robert Gibson supervises the emergency section in the DNR's mines and minerals department. He says two-thirds of Illinois was mined for coal, so the risk to structures is widespread.