In 1937, the state government created a commission to study bootleg coal. They launched an extensive survey to map out bootleg coal operations in Schuylkill and Northumberland counties, using airplane and employing 20 unemployed miners to go site to site. They had the cooperation of the Independent Miners’ Association and most coal bootleggers.
Published in 1938, the commission found 7,000 people working together in 1,129 illegal mines across Schuylkill, Northumberland, Columbia, and Dauphin counties. They estimated another 250 coal holes existed in Carbon, Luzerne, and Lackawanna counties. Another 1,300 worked in small breakers and 2,700 truckers ran the coal to market.
Approximately 2/3rd of all bootleg mines were in Schuylkill County. Below, you can see the commission’s map of active bootleg mines in there in late 1937.
You can read a 108-page excerpt from the Anthracite Coal Industry Commission at archive.org . Or if you’d really like to melt your brain, read the full 1223-page report.