Delinquent Mines: About The Data Details on how NPR analyzed data to report stories about millions of dollars in fines and thousands of injuries and violations piled up at mines that don't pay their penalties.

Delinquent Mines: About The Data

NPR and Mine Safety and Health News analyzed Mine Safety and Health Administration (MSHA) records for our series Delinquent Mines. Among them were detailed reports of mines that had delinquent debt. The debts in those reports were all considered final — either unchallenged by mine operators or upheld in an appeals process.

We compared the delinquency reports with other publicly available Department of Labor data on mine safety violations and mine injuries, looking specifically at injuries and violations that occurred during each mine's period of delinquency.

By law, penalties are assessed against mine operators, which may be subsidiary companies of a "controller," or corporate owner. However, we aggregated data by controller to show the total owner or corporate debt. Total debt for each mine controller is based on the controller of record at each mine at the time the fine became delinquent.

Injury rates were calculated by NPR taking raw Department of Labor data and applying MSHA's prescribed formulas and injury categories. The rates we calculated for delinquent mines apply only to the years of delinquency.

Coal tonnage is based on annual data provided by the Department of Labor. Tonnage is included only for full years of delinquency. Coal value was estimated using average annual sales prices provided by the Energy Information Administration for each mine type and the relevant state or region within the state (if available). The estimates do not include 2013 or 2014 prices because price data were not yet available.

In the "Top 10 Mining Companies With Outstanding Fines" chart, the "Controller/Owner" is as reported by MSHA. Violations by mine operators, cited and reported by MSHA, are often subsidiary companies of the controller/owner. "Injuries And Violations" during delinquency do not include delinquencies categorized as "on hold" or 1 to 90 days old.