Description: ÒProduction of coal in the United States in 1918 and outlines [in red] of coal fieldsÉ Size of block is proportional to percentage of total production of the United States in 1918; percentage indicated also by figuresÉ Approximate outlines of coal fields other than lignite. Most important producing districts shaded. — Department of the Interior, 1921
Source: Department of the Interior , World Atlas of Commercial Geology (Washington, DC: Department of the Interior , 1921) Plate 8
Map Credit: Courtesy the private collection of Roy Winkelman |
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