 US 421 heads northwest and passes through the hamlet of Woodway before crossing the Powell River.The U.S. Highway follows the North Fork of the Powell River to the town of Pennington Gap, where the highway passes under the Appalachia Division rail line intersects US 58 Alternate (Trail of the Lonesome Pine).US 421 and US 58 Alternate head through the center of town along Morgan Avenue before US 421 heads out of town along the North Fork of the Powell River and the rail line through Pennington Gap, which is a water gap through Stone Mountain.