The U.S. Geological Survey (USGS) has completed the National Coal Resource Assessment (NCRA), a multiyear project by the USGS Energy Resources Program, in partnership with State geological surveys in the coal producing regions of the United States. The NCRA is the first digital national coal-resource assessment. Coal beds and zones were assessed in five regions that account for more than 90 percent of the Nation's coal production - (1) the Appalachian Basin, (2) the Illinois Basin, (3) the Gulf Coastal Plain, (4) the Colorado Plateau, and (5) the Northern Rocky Mountains and Great Plains. The purpose of this Professional Paper, USGS Professional Paper 1625-F, is to present a tabulation and overview of the assessment results, insight into the methods used in the NCRA, and supplemental information on coal quality, economics, and other factors that affect coal production in the United States.