Until that point, oil that seeped to the surface had been collected for use in medicines. But Drake's well and those that followed answered a demand for better lighting fuels than the whale oil commonly used then.

"The market was building for a way to push back the darkness," said oil industry historian William Brice of the University of Pittsburgh at Johnstown.

Titusville swelled from a couple hundred residents to more than 10,000 as oil companies snapped up drilling leases and hired laborers. Teamsters arrived to transport barrels of fuel by horse-drawn wagon.

Compared to modern drilling methods and controls, "No attention paid to the environment -- oil spilled all over the place," Lou D'Amico of the Independent Oil and Gas Association of Pennsylvania said.

The region grew for decades and producers became millionaires as the internal combustion engine presented a new use for oil. But Pennsylvania's oil industry peaked in 1891 and drillers moved west as supplies dwindled.

Local energy production firms are betting that won't happen this time.

Solar Power Industries Inc. of Rostraver anticipates domestic sales for its energy-producing panels will jump because of renewable energy use incentives that are part of the $787 billion federal economic stimulus package.

"Everyone is poised for the U.S. to come on line with solar power," said Rob Lazzari, vice president of resource management. The company expects to spread some of its production within a month to part of the former Sony Corp. plant in East Huntingdon, Westmoreland County.

At this point, Lazzari said, 98 percent of the company's products are sold outside the United States, mainly in China and Germany.

German-owned Flabeg Corp., meanwhile, is building a plant in Findlay that will make glass and mirror components for panels in large-scale solar power plants and could employ 200 people at the plant by next year. And Spain's Gamesa SA is expanding the Ebensburg, Cambria County, plant it opened three years ago to make windmill blades.

But natural gas is the developing industry with the most dramatic local impact these days.

New drilling technologies make the Marcellus Shale formation -- 6,000 feet or more underground -- reachable, and rising demand in recent years makes going after it worthwhile.

About 500 Marcellus wells have been drilled so far in Pennsylvania. Drillers from Texas, Louisiana and other states have been working here temporarily, but the companies are hiring and training local workers and could create about 8,000 jobs this year.

Texas-based gas producer Range Resources LLC opened an office in Cecil, Washington County, with one employee in January 2007 and now has 130.