"Donald Trump says he would bring back lost coal-mining jobs, and he is positioning for the November election in big coal states by portraying Hillary Clinton as a job killer.
Trump, however, has yet to explain exactly how he will revitalize Appalachia’s coal industry. To pull it off, he will have to overcome market forces and a push for cleaner fuels that have pummeled coal.
Coal’s slump is largely the result of cheap natural gas, which now rivals coal as a fuel for generating electricity. Older coal-fired plants are being idled to meet clean-air standards.
Another hurdle for reviving coal mining in Appalachia: less coal. Reserves of coal still in the ground are smaller than in western states like Wyoming, the leading coal producer.
According to the Labor Department, there were 56,700 jobs in coal mining in March, down from 68,000 just a year earlier."
http://www.sfgate.com/nation/article/Trump-s-pledge-to-create-Appalachian-coal-jobs-7396292.php