Coal production in the first three months of 2016 was 173 million short tons, the lowest quarterly level in the United States since a major coal strike in the second quarter of 1981. Among the regions tracked by the EIA, the Powder River Basin (PBR) in Montana and Wyoming saw the largest decline both in terms of absolute tonnage and as a percentage of the previous quarter.Demand for coal has dropped off steeply as natural gas becomes the primary fuel source for electrical generation. Electricity generation accounts for more than 90% of domestic coal use, but environmental regulations have caused...