The Midwest continues to rely more on coal than other region of the U.S., despite a big drop in coal use in the past decade.

The region generated 46 percent of its electricity from coal in 2017, down from 72 percent in 2005, according the Energy Information Administration’s Midwest census region data.

The reductions in Midwest coal use will continue because of utilities’ voluntary reductions and, to a lesser degree, federal and state policies: Constructing new coal plants is making less economic sense, and it’s expensive to continue maintaining existing ones, compared to lower-carbon natural gas and zero-carbon...