Saw Mill Run Boulevard is a heavily traveled four-lane Pittsburgh, PA road that passes through South Pittsburgh.

Saw Mill Run Boulevard is the Pittsburgh name for the stretch of PA Route 51 – a major state traffic artery – that passes through the city starting at the intersection of Clairton Road and Stewart Avenue, where Overbrook borders Brentwood Borough.

Saw Mill Run Boulevard travels north through Overbrook.

AHN Brentwood Neighborhood Hospital, a microhospital that provides an emergency room, diagnostic imaging, laboratory services and overnight care when needed for people who live in South Pittsburgh and the South Hills, is on Saw Mill Run Blvd in Brentwood.

The road borders Carrick and Brookline.

Route 88 ends at Saw Mill Run Boulevard.

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 is a four-lane road for its entire length.

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 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.

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.

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