Saw Mill Run Boulevard is the Pittsburgh name for State Route 51. It is a heavily traveled road that passes through South Pittsburgh.

Saw Mill Run Boulevard travels north through Overbrook.

Route 88 (Library Road) ends at Saw Mill Run Boulevard.

The entrance to Seldom Seen Greenway is located off Saw Mill Run Boulevard.

Saw Mill Run Boulevard borders Carrick and Brookline.

North of 88, Saw Mill Run Boulevard intersects with the Liberty Tunnel and West Liberty Avenue. Saw Mill Run Boulevard crosses the Parkway West at the Fort Pitt Tunnel. Having a Pittsburgh-specific name ends at the West End and the West End Bridge, where it’s known as the West End Circle or West End Bypass.

Saw Mill Run Boulevard follows Saw Mill Run, an urban stream that drains water from Pittsburgh and portions of Castle Shannon and Bethel Park, emptying into the Ohio River around Pittsburgh’s Point.

South Bank Station sits along Saw Mill Run Boulevard. South Bank is a major transit facility that provides connections to buses, and the Blue Line and Silver Line light rail service for people in the area.

The South Busway parallels Saw Mill Run Boulevard. The busway, operated by the Port Authority of Allegheny County, runs commuter buses into downtown Pittsburgh. The busway avoids the traffic congestion on Saw Mill Run Boulevard during the hours that people travel to and from work.

State Route 51

North of Pittsburgh, Route 51 passes through several boroughs along the Ohio River, into Beaver County and towards Ohio.

At the other end, PA Route 51 starts in Uniontown, Fayette County. It carries traffic north from Uniontown and the rest of Fayette County into Pittsburgh.

Route 51 is mostly four lanes, although it’s restricted to two lanes along some stretches outside of Pittsburgh. It is a major state traffic artery.

History

Route 51 was constructed as America took to the roads in cars in the 1920s. After the Liberty Tunnel was built, the route provided the first decent connection from the South Hills into Pittsburgh. It dropped the driving time into Pittsburgh from McKeesport, Clairton and Duquesne, which were important cities along the Mon Valley at the time.

The road was “originally proposed by famed planner, Robert Moses,” according to the Carrick-Overbrook Historical Society. Moses was a powerful and influential man who shaped modern America by favoring highways over public transit, leading to mass migration into the suburbs. A landmark biography accused Moses of questionable ethics and racism.

The route into Pittsburgh from the south was so popular – so congested – that for half a century the intersection where Route 88 ends at Route 51 gave motorists headaches. The first discussions about fixing the bottleneck started in the mid 1960s. The Route 51/Route 88 intersection was finally fixed in the 2010s.