CENTERTOWN, Ky. - A five-minute drive from this community's lone gas station leads to a gateway to untapped riches: A bed of coal twice the size of Lake Michigan.

Earth-movers are peeling back layers of dirt and limestone here at the Midway mine and at other once-abandoned mining sites around the Illinois Basin, a coal-rich region that reaches into Illinois, southwestern Indiana and northwestern Kentucky.

The mechanical rumbling means the return of lucrative mining jobs to a territory crippled by the exodus of coal mining companies that began more than 30 years ago.

"I guess we can call it the rebirth of coal," said David Jones, a former miner in his first term as judge-executive of Ohio County, Ky., where the unemployment rate hovers around 9 percent.

The resurgence has breathed life into communities the industry nearly killed when it left. And it's all possible thanks to technological strides that make burning such coal less harmful, improvements that resulted, ironically, from pressure by the environmental movement.

Coal companies see a bright future in the Illinois Basin, after a steady retreat from the region beginning in the 1970s. Federal air restrictions during that decade made it tougher to market the basin's coal, because it emitted more sulfur dioxide when burned compared to coal from Appalachia and western states.

Environmentalists worry that scraping out the basin's reserves will simply encourage the energy industry to prop up its aging coal-fired power plants when the country should be shifting to alternative sources. The Illinois Basin is close to the country's densest cluster of coal-fired power plants, which are nestled along the Ohio River and pump power onto a grid that supplies millions far beyond the Midwest.

In a country where half the generated electricity comes from coal, the Illinois Basin's vast reserves are attracting new mine openings, including plans in Indiana for the largest surface mine east of the Mississippi River.

Total U.S. coal production was down nearly 6 percent so far in 2009 due to slowing demand, but in Illinois, Indiana and western Kentucky it's up from 1 to 5 percent, according to the Department of Energy. Western Kentucky's production was up 6.4 percent over a 52-week period ending last month.

The surface mine near Centertown, 90 miles southwest of Louisville, sat abandoned just a couple of years ago, before newly formed Armstrong Coal Co. bought the reserves and several others in the area.

The St. Louis-based firm, started by pharmaceuticals entrepreneur J. Hord Armstrong, exemplifies the region's resurgence. The company began buying coal reserves from Peabody Energy Corp.