Pennsylvania Route 51 (PA 51) is a major state highway in Western Pennsylvania. It runs for from Uniontown to the Ohio state line near Darlington, where it connects with Ohio State Route 14. PA 51 is the termination point for Pennsylvania Route 43, Pennsylvania Route 48 and Pennsylvania Route 88. The route is a major connection from Uniontown and the rest of Fayette County to Pittsburgh. The highway is four-lane highway south of Pittsburgh as it passes through Pittsburgh's South Hills, but narrows to a two-lane road through several boroughs along the Ohio River. It becomes four lanes again after passing Chippewa Township in Beaver County and continues to the Ohio border. In the South Hills, PA 51 (Saw Mill Run Boulevard), along with US 19, is one of the major routes in and out of Pittsburgh, as it provides access to several bridges and tunnels. PA 51 is one of the highways that enters the West End Circle, an intersection in the West End. Route description Fayette and Westmoreland counties PA 51 begins as Pittsburgh Street in downtown Uniontown at an intersection with U.S. Route 40 Business. As PA 51 heads north, it exits Uniontown and intersects with U.S. Route 119, Uniontown's bypass. North of US 119, PA 51 is a rural, multi-lane divided highway that is also known as Pittsburgh Road. In North Union Township, PA 51 divides for ; the road has a large median that is home to several businesses. It then shifts towards the northwest, continuing as a multi-lane divided highway. In Perry Township, PA 51 intersects Pennsylvania Route 201 at a cloverleaf interchange. North of PA 201, it enters the borough of Perryopolis as Fuller Drive; after leaving the city to the north, PA 51 begins to parallel the Youghiogheny River. Upon entering Westmoreland County, PA 51 intersects the southern terminus of Pennsylvania Route 981. About northwest of PA 981, it also intersects Interstate 70 at exits 46 A-B to form a full cloverleaf interchange. To the northwest in Sweeneys Crossroads, the road intersects Pennsylvania Route 201 again. PA 51 divides before reaching the county border and also passes by Rostraver Airport. Route 51 only spends seven miles (11 km) in Westmoreland County, all in Rostraver Township. Allegheny and Beaver counties Upon entering Allegheny County, PA 51 is called Hayden Boulevard, and it meets with Pennsylvania Route 136 at a diamond interchange. PA 51