WASHINGTON — In Page, Ariz., the operators of the Navajo Generating Station, the largest coal-fired power plant in the West, have announced plans to close it by 2019. The electric utility Dayton Power & Light will shut two coal plants in southern Ohio by next year. Across the country, at least six other coal-fired power plants have shut since November, and nearly 40 more are to close in the next four years.

President Trump campaigned on a pledge to restore the limping American coal industry, vowing to bring jobs and production back to a sector that has been on a steady decline for over a decade. But to do that, he would have to revive demand for coal by electric utilities, which for decades have been the largest consumer of the heavily polluting fuel. Nearly all the coal mined in the United States generates electricity.

On March 28, Mr. Trump headed to the Environmental Protection Agency, where, flanked by coal miners and coal company executives, he signed an executive order directing the agency’s administrator, Scott Pruitt, to begin rolling back a set of regulations on coal-fired power plant pollution that made up the centerpiece of President Obama’s climate change legacy.

“Today I’m taking bold action to follow through on that promise,” Mr. Trump told the miners. “My administration is putting an end to the war on coal.”