Inexpensive natural gas, lower international coal demand and U.S. environmental regulations have led to a precipitous decline in U.S. coal production, according to the U.S. Energy Information Administration. After hitting a high in 2008 output in 2015 dropped to the lowest level since 1986. (See interactive graphic below.) Production fell 10 percent from 2014 alone, the EIA says, with big declines in Kentucky and Virginia. Exports in 2015 decreased by 21 percent compared with 2014.