Located in Fayette and Westmoreland Counties, this region's abundant high-quality Pittsburgh vein coal yielded superior coke used to smelt iron. This refined form of coal was produced in beehive ovens from the mid-19th century to the 1970s. Immigrant and migrant workers who settled here after the Civil War provided labor for the booming coke industry. Byproduct ovens built near steel mills eventually rendered beehives obsolete.