heads east through a mix of rural areas and development parallel to a Buffalo and Pittsburgh Railroad line located south of the road to the borough of Youngsville, where PA 27 splits to the north. At this point, US 6 becomes a four-lane divided highway called the Youngsville Bypass that crosses Brokenstraw Creek and heads to the south of Youngsville. East of the borough, the route comes to an interchange with East Main Street that provides access to Youngsville and Irvine. The highway heads east through rural areas alongside the Brokenstraw Creek and reaches a trumpet interchange with US 62. At this point, US 62 heads east for a concurrency with US 6, and the road runs through wooded areas and development to the north of a Buffalo and Pittsburgh Railroad line and the Allegheny River, transitioning into a five-lane road with a center left-turn lane. The road becomes a four-lane divided highway again and reaches the city of Warren, where it passes over the railroad and US 62 and US 6 Business (US 6 Bus.) head northeast into the central part of the city at an interchange. US 6 crosses the Allegheny River and passes through developed areas in the southern part of Warren, reaching an eastbound exit and westbound entrance at Main Avenue. Past this interchange, the divided highway narrows to two lanes before the road curves to the southeast and becomes a two-lane undivided road that runs through wooded areas with a Buffalo and Pittsburgh Railroad line and the river to the northeast. At the southeast edge of Warren, the roadway crosses the railroad tracks and US 6 Bus. returns to US 6 at an intersection. Warren to Mansfield After passing Warren, US 6 reaches an intersection with the western terminus of PA 59, which heads east to follow the Allegheny River. From here, the route continues southeast into the Allegheny National Forest, winding to the south parallel to a Buffalo and Pittsburgh Railroad line as it enters mountainous terrain. US 6 passes southeast through developed areas of the borough of Clarendon along North Main and South Main streets. Past here, the road heads south-southeast through more of the national forest, with occasional development along the road. In the community of Sheffield, the route comes to an intersection with the eastern terminus of PA 666 and curves to the east. US 6 continues through rugged forests and