President Trump vows to "end the war on coal" and put miners back to work. Efforts to uphold that campaign pledge include rolling back some environmental policies of his Democratic predecessor and allowing new coal leases on public lands. "We're going to fight for you," Trump said at a ceremony with mine union leaders. But energy specialists, labor economists and coal executives see limits on expanding employment significantly in light of increased automation and declining demand for coal.

Coal workers in West Virginia, Pennsylvania, Ohio, Kentucky and elsewhere were among voters backing Trump last fall. To repay their support, he promises to work with Republicans in Congress to balance environmental concerns with economic recovery in mining regions. "We're going to have clean coal -- really clean coal," the president said recently as he signed an executive order to "lift the restrictions on American energy, to reverse government intrusion and to cancel job-killing regulations." (See video below.)

But his employment goals conflict with mining advances that require fewer workers, with greater reliance on natural gas and with state economic development policies discouraging coal use. For instance, the Caterpillar company has a new system that lets one worker control three drills at once. And a shift to surface mines — which involves opening mountains with controlled explosions, then using automated heavy machinery to mine the coal — also brings a steep decline in jobs. In 1980, the industry employed about 242,000 people. By 2015, employment plunged below 100,000, even as coal production rose slightly.

Another factor limiting the growth of mine jobs is the growing popularity of cheap, abundant natural gas and renewable energy sources such as solar, wind and hydroelectric power. Coal now fuels just a third of electricity generation in the United States. At the same time, coal exports are falling as other countries also turn to alternatives. "Regardless of what Trump does, the future lies in renewable energy sources," says a Los Angeles Times editorial.

President says: "I made my promise and I keep my promise. . . . We will put our miners back to work." – March 28, signing executive order at Environmental Protection Agency

Coal executive says: "I've suggested to Mr. Trump that he temper his expectations. . . . If he just stops [the industry decline] where it is, that will be a wonderful thing." – Robert Murray, chief executive of Murray Energy, the largest U.S. private coal miner

Columnist says: "Environmentalism is a minor factor in coal's decline." – Paul Krugman, The New York Times