There was a time when coal was king in Pennsylvania, when hundreds of thousands of miners produced hundreds of millions of tons of coal each year — and too many died doing it.

Those days are gone.

In 2000, the most recent year for which figures are available, there were just 8,668 miners in the state, and they dug 78.3 million tons of coal. One died.

Compare this to 1907, when nearly 352,000 underground miners produced 235.6 tons of anthracite and bituminous coal, and 1,514 died.

Today, Wyoming, West Virginia and Kentucky all produce more coal than does Pennsylvania.

So the accident that trapped nine miners at the Black Wolf mine, 55 miles southeast of Pittsburgh, harkened back to an age gone by when Pennsylvania's working mines were far more plentiful and less safe.

There are two kinds of coal. Anthracite, long associated with residential heating, has a much higher carbon content than bituminous coal, which is used primarily to generate electricity and make coke for the steel industry.

During the first third of the 20th century, Eastern Pennsylvania's anthracite coal heated homes in most of the northeastern United States. But historians say homeowners fretted about going cold during coal strikes and looked elsewhere, to more convenient alternatives like home heating oil and natural gas.

About 2,000 people are believed to work on anthracite now, mostly taking coal from old waste piles, even though an estimated 7 billion tons of the coal remain underground.

The coal industry in west-central and southwestern Pennsylvania, where the bituminous coal has more sulfur and burns dirtier, lost customers as tougher federal laws required power plants to pollute less.

With advances in technology and strengthening government oversight, safety in mines has vastly improved.

The Black Wolf mine is a relatively small, 65-employee operation. Since opening in January 2001, it has been cited for 26 safety violations — from having inexperienced miners to combustible materials — and ordered to pay fines of $856, federal Mine Safety and Health Administration records showed. A 30-foot by 40-foot section of the roof collapsed in October but no one was injured.

Mark Radomsky, director of field services for Penn State's Miner Training Program, which provides training for the Black Wolf miners, said his instructor described the mine as well run.

While the facts remain to be determined, Radomsky said, "You can speculate that they were mining by the book. What they didn't know is that they were perilously close to those abandoned works."