Saw Mill Run is a

tributary A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainag ...

of the Ohio River in

Pennsylvania Pennsylvania (; (Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, Ma ...

. It is an

urban stream An urban stream is a formerly natural waterway that flows through a heavily populated area. Urban streams are often polluted by urban runoff and combined sewer outflows. Water scarcity makes flow management in the rehabilitation of urban streams ...

, and lies entirely within

Allegheny County, Pennsylvania Allegheny County () is a county in the Commonwealth of Pennsylvania. It is located in Southwestern Pennsylvania. As of the 2020 census, the population was 1,250,578, making it the state's second-most populous county, following Philadelphia ...

. The stream enters the Ohio just downstream from the Forks of the Ohio in

Pittsburgh Pittsburgh ( ) is a city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, United States, and the county seat of Allegheny County, Pennsylvania, Allegheny County. It is the most populous city in both Allegheny County and Wester ...

, at a place that was founded as the town of Temperanceville in the 1830s. It provides an entry through the elevated plateau south of Pittsburgh known as the South Hills, and land transportation has paralleled the stream since the nineteenth century. The stream is named for an actual saw mill that operated near the mouth of the stream where it empties into the Ohio River. The first reference to the mill is in relation to the construction of Fort Pitt (1759–1761). The mill provided much of the lumber used in the construction of the new Fort, after the British claimed the area from the French and destroyed

Fort Duquesne Fort Duquesne (, ; originally called ''Fort Du Quesne'') was a fort established by the French in 1754, at the confluence of the Allegheny and Monongahela rivers. It was later taken over by the British, and later the Americans, and developed a ...

Railroads

The

Coal Hill Coal Railroad The Coal Hill Coal Railroad began as a coal mine on the north face of Mt. Washington, then known as "Coal Hill", begun by Jacob Beltzhoover in 1825. This mine was operated by a series of persons, finally by James M. Bailey, who extended the mine ...

crossed the stream on a trestle, and extended upstream in 1861. This railroad was purchased by the Pittsburgh and Castle Shannon Railroad, who extended the line to follow the main stream of Saw Mill Run from the

Pittsburgh and Castle Shannon Tunnel The Pittsburgh and Castle Shannon Tunnel, also known as the Mount Washington Coal Tunnel, was a narrow-gauge railway tunnel under Mt. Washington. History It was originally begun as a coal mine in 1825 by Jacob Beltzhoover. The mine was exten ...

Castle Shannon, Pennsylvania Castle Shannon is a borough in Allegheny County, Pennsylvania, United States, and is part of the Pittsburgh Metro Area. The population was 8,316 at the 2010 census. Geography According to the United States Census Bureau, the borough has a total ...

. The Little Saw Mill Run Railroad followed the west branch of the stream towards

Mt. Lebanon, Pennsylvania Mt. Lebanon is a township with home rule status in Allegheny County, Pennsylvania, United States. The population was 34,075 at the 2020 census. It is a suburb of Pittsburgh. Established in 1912 as Mount Lebanon, the township was a farming com ...

. The Wheeling and Lake Erie Railway (W&LE) operated a short rail line on the western end of the stream, known as the West End Branch. It had been used by the Pittsburgh and West Virginia Railway as a connection with the

Pittsburgh and Lake Erie Railroad The Pittsburgh and Lake Erie Railroad (P&LE) , also known as the "Little Giant", was formed on May 11, 1875. Company headquarters were located in Pittsburgh, Pennsylvania. The line connected Pittsburgh in the east with Youngstown, Ohio in the H ...

near West Carson Street. The W&LE operated it until late 2008, and most of the line has been torn up, with the crossing signal cantilevers on Steuben Street being removed in 2012.

Trolley and light rail

The right of way of the Pittsburgh and Castle Shannon, excluding the Pittsburgh and Castle Shannon Tunnel through a coal mine, was leased by

Pittsburgh Railways Pittsburgh Railways was one of the predecessors of Pittsburgh Regional Transit. It had 666 PCC cars, the third largest fleet in North America (after Toronto (745) and Chicago (683)). It had 68 streetcar routes, of which only three (until April ...

in 1905, and later purchased in 1950. The railroad ran with a dual gauge system, with coal trains continuing to run on the narrow gauge, and at night, and trolleys on a wider gauge. The right of way is part of the

Pittsburgh Light Rail The Pittsburgh Light Rail (commonly known as The T) is a light rail system in Pittsburgh, Pennsylvania, and surrounding suburbs. It operates as a deep-level subway in Downtown Pittsburgh, but runs mostly at-grade in the suburbs south of the c ...

transportation system today, which follows the stream from near the South Hills Junction (PAT station) to Castle Shannon, Pennsylvania.

Highways

Part of

Pennsylvania Route 51 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 ...

runs parallel to the stream, and this section is known as Saw Mill Run Boulevard.

Watershed

The watershed of Saw Mill Run covers , or about . The main stream is long, and drains parts of Bethel Park, Castle Shannon, Mount Oliver, and the city of Pittsburgh.

References

{{authority control Pittsburgh metropolitan area Rivers of Pennsylvania Tributaries of the Ohio River Rivers of Allegheny County, Pennsylvania

Railroads

Trolley and light rail

Highways

Watershed

See also

References