Democratic Gov. Tom Wolf said the mine was part of an effort to bring back jobs and industry to the state. Pennsylvania awarded a $3 million grant for the project.

“We have not always capitalized on our standing as one of the world’s leaders in these resources, but we’re changing that,” Wolf said.

Trump has made reversing the decades-long decline in coal mining the central tenet of his environmental policy, blaming federal regulations aimed at curbing planet-warming carbon emissions for job losses in the industry. Trump and Environmental Protection Agency Administrator Scott Pruitt have targeted laws that protected waterways from coal waste and required states to slash carbon emissions from power plants. About a dozen protesters chanted in opposition to the mine at the opening.