Significant coal resources exist in about 18 counties in southwestern Indiana. In 2002, coal was produced in 11 of those counties. The top five producing counties were Gibson, Greene, Knox, Pike, and Vigo. Coal is produced from as many as 10 different coal beds.
Persons interested in determining if any particular area has been undermined in the past can consult the Coal Mine Information System of the Indiana Geological Survey (IGS).
A great deal of information about the geology and other characteristics of Indiana's coal beds is available from the Indiana Geological Survey (keyword "coal"). A concise summary of much of that information is provided by the following publication: Mastalerz, M., and Harper, D., 1998, Coal in Indiana: A geologic overview. Indiana Geological Survey Special Report 60, 45 p.