HOW IS ILLINOIS COAL MINED?
In Illinois there are two main ways of mining coal: strip (open-cut) and underground. Strip or open-cut mines ([fig. 11]) usually operate where the coal is at very shallow depths, although such mining is done as much as 100 feet deep or more in some places. Many old underground mines produced coal from seams that were less than 100 feet deep because they did not have the large machinery for strip mining when these mines were started. An abandoned mine, 1,004 feet deep, near Assumption is the deepest underground coal mine in the state. Coal is now being mined at depths somewhat over 800 feet in Jefferson County.