From 1985 to 1994, a series of reports on coal resources of selected counties in Indiana was published as part of the Special Report series of the Indiana Geological Survey. These reports included maps showing thickness of the Springfield Coal Member (Petersburg Formation, Pennsylvanian). The thickness maps were based on coal-test records, mine-map notations, and interpretations of geophysical logs that are included in the files of the Indiana Geological Survey. Data points were plotted by coal geologists of the Indiana Geological Survey and thickness contours were drawn by hand. The original work maps were compiled at a scale of 0.5 inch = 1 mile (1:126,720). Following completion of the investigations, the work maps showing thickness contours were subsequently scanned and digitized, and the resulting county coverages were then compiled into a single multi-county coverage. Different thickness ranges were utilized in the various counties; these thickness ranges (given in feet) are retained in the final map. Since the completion of this shapefile, additional data on coal thicknesses in selected areas has been obtained by the Indiana Geological Survey; interested users may wish to contact the Indiana Geological Survey for information on these more up-to-date sources.