By MATTHEW BROWNSHERIDAN, Wyo. (AP) â¿¿ Hundreds of millions of tons of coal, packed into seams up to 60 feet thick, are still to be had beneath the rock-strewn hillsides speckled with snow that rise up along the remote Montana-Wyoming border. Yet for Mike Cooley, the days of drilling explosives into the ground to blast the fuel from the earth are over, long before he ever expected. The 41-year-old thought his job as a "powderman" at the Decker strip mine would take him into retirement. Now he's looking for new work, after he and 58 other miners were laid off from Decker in recent weeks to add to several hundred jobs reported lost in the past year from the nation's largest coal-producing region. As a dispute over West Coast ports hobbles the industry's ability to reach booming markets in Asia, cheap natural gas is undercutting coal in the U.S. â¿¿ and putting some of the small towns in coal country in economic peril. Wringing his calloused, idle hands and staring into the winter sun through the kitchen window of his trailer house in Sheridan, not far from the mine, Cooley said he's reluctant to leave with the eldest of his three children poised to graduate high school this spring. "But I don't want to go back to pounding nails either, not at $13 an hour," the former construction worker said as his youngest child, two-year-old Mason, hovered nearby sucking on a lollipop. For decades, the 25,000-square-mile Powder River Basin that surrounds Sheridan has been the stronghold of the U.S. coal industry. Massive strip-mines, carved from a landscape dominated by sage brush and cattle ranches, churn out close to a half-million tons of the fuel annually, dwarfing production from mines in the Appalachians and Midwest. Now the depressed domestic coal market is finally catching up to mines such as Decker. At least 300 jobs have been lost from mines in Montana and Wyoming since early 2012, according to preliminary data from the Mine Safety and Health Administration.