The low price of natural gas has meant tough competition for the coal industry. Production is down across the country, except, it turns out, in Illinois.
By some measures, Illinois coal is not as pure as what's mined in the Appalachian Mountains or out west.
It doesn't generate as much heat and has more pollutants, so it commands a lower price than other types of coal. But lately, that's been an asset.
Tejasvi Raghuveer is an industry economist with the U.S. Energy Information Administration, an independent, non-partisan federal agency. She says a lot of coal-burning power plants in the area have added anti-pollution equipment so they can legally burn the higher-sulfer Illinois coal.
"In that region, we found 30 plants representing about 31 gigawatts of capacity that added scrubbers from 2007."
The average demand in New England is roughly about 25 gigawatts.
With so many plants able to burn the lower-cost Illinois coal, demand has stayed relatively strong.
While overall U.S. coal production is down, Illinois coal was up 13 percent in the first part of this year.
And eight new mines have opened since 2010, including five this year alone.
Illinois Public Radio's Brian Mackey contributed to this report