McConnells Mill State Park in western Pennsylvania unites dramatic natural scenery with a remarkably intact nineteenth-century industrial landscape. Centered on McConnell’s Mill, first opened as a gristmill by Daniel Kennedy in 1852, the site evolved under Thomas McConnell after 1875 into one of the country’s earliest rolling mills before closing in 1928. A restored mill and the 1874 McConnells Mill Covered Bridge still stand on the gorge floor. The park’s deep Slippery Rock Creek gorge was shaped by ancient bedrock and a glacial-lake breakthrough about 140,000 years ago. Today the area is also known for hiking, whitewater boating, climbing, and rappelling within an important Appalachian forest setting.