In the past 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 Danville Coal Member (Dugger 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. Different thickness ranges were used in the various counties and for different purposes. Since 1980, staff members of the Indiana Geological Survey (IGS) have also collected and entered coal resource information into the NCRDS database as a cooperative project with the U.S. Geological Survey (USGS). The purpose of NCRDS database is to provide a means of rapid retrieval of point-source coal resource information, including coal location, thickness, depth, and other parameters. Based on all available data as of October 2010, a new map of Danville Coal Member thickness was created. It is the most current thickness map of the Danville Coal Member. Because additional data on coal thicknesses are obtained by the Indiana Geological Survey on an annual basis, interested users may wish to contact the Indiana Geological Survey for information on these more up-to-date sources.