Pennsylvania holds the distinction of having one of the highest concentrations of abandoned coal mines in the United States, a direct result of its extensive history of deep and surface anthracite and bituminous coal mining dating back to the early 19th century. Other states with legacy industrial footprints, such as West Virginia, Kentucky, Ohio, and Illinois, also account for tens of thousands of abandoned mine lands. These sites present ongoing environmental, safety, and land reclamation challenges managed closely by state agencies and the federal Office of Surface Mining Reclamation and Enforcement.