2001. Eastern Energy Resource Surveys Team (Geological Survey). This polygon shapefile shows the coal fields of Alaska and the conterminous United States. Most of the material for the conterminous United States ... National Atlas of the United States.
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Compiled from maps by U. S. Geological Survey ; Breuker & Kessler Co. Phila. Coordinates approximate and based on Greewich meridian. Relief shown b... U. S. Geological Survey,.