The more important changes in the American coal industry during the past fifty years have been brought about through the increasing reliance upon mechanization, automation, and management. The changes have been made possible mainly by industrial research, experimentation, and testing, particularly in the fields of mechanical engineering, preparation, and utilization, and by concentration of management. Paralleling such investigations, particularly in government laboratories and geological surveys, have been investigations that concern the mapping and evaluation of resources, on the one hand, and those that concern the basic physical constitution of coal, on the other. The growing pressure being exerted on the already occupied coal reserves, particularly in the eastern part of the country, makes of constantly increasing importance a knowledge of the remaining resources. The increasing use of mechanical methods of mining, accompanied by the increasing production of finer and finer sizes and the attendant increase in mineral impurities in such coal, makes automatic cleaning increasingly essential. It is obvious that these two tendencies approach a condition of diminishing return in terms of ash reduction alone. In the petrographic heterogeneity of coal established by coal petrology, there resides the possibility of more discriminating refinement in preparation than has yet been achieved, particularly with the lower rank bituminous coals. Thus both the study of coal resources and of coal petrology may be rightly included in the general field of applied or economic geology.