Coal is still a major source of energy in the United States. But coal consumption is on track to hit a near-40-year low in 2018, according to the U.S. Energy Information Administration. And economists and industry watchers say that decline is likely to continue, because of competition from cheaper alternatives like natural gas, because new technologies are increasing energy efficiency, and because renewable energy sources like wind and solar are more competitive in the energy marketplace.

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Correction (Dec. 6, 2018):  The original audio introduction to this story misidentified the Environmental Protection Agency. That audio has been deleted.