Saw Mill Run

Saw Mill Run
The Seldom Seen Arch, built in 1903, over Saw Mill Run along Saw Mill Run Boulevard not far from Woodruff Street in the Mount Washington neighborhood of Pittsburgh, Pennsylvania
Basin
Main source	Castle Shannon, Pennsylvania
River mouth	Ohio River
Basin size	19 sq mi (49 km2)
Physical characteristics
Length	9.3 mi (15.0 km)

Saw Mill Run is a tributary of the Ohio River in Pennsylvania. It is an urban stream, and lies entirely within Allegheny County, Pennsylvania. The stream enters the Ohio just downstream from the Forks of the Ohio in Pittsburgh, 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 Coal Hill Coal Railroad 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 to Castle Shannon, Pennsylvania. The Little Saw Mill Run Railroad followed the west branch of the stream towards Mt. Lebanon, Pennsylvania.

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 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.