Preliminary numbers released by the U.S. Energy Information Administration indicate Wyoming mines produced about 9 percent less coal in 2012 than in 2011.
Mines in the state produced an estimated 398 million tons in 2012, compared to 436 million tons in 2011. Nationwide, coal production dropped about 7 percent.
Industry officials say the decrease in production is due to sagging natural gas prices, a mild winter and stricter regulations on coal-burning power plants.
