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

The W&LE operated it until late 2008,[8][9] and most of the line has been torn up, with the crossing signal cantilevers on Steuben Street being removed in 2012.

The right of way is part of the Pittsburgh Light Rail transportation system today, which follows the stream from near the South Hills Junction (PAT station) to Castle Shannon, Pennsylvania.

The watershed of Saw Mill Run covers 12,432 acres (50.31 km2), or about 19 square miles (49 km2).

The main stream is 9.3 miles (15.0 km) long, and drains parts of Bethel Park, Castle Shannon, Mount Oliver, and the city of Pittsburgh.