Gar Run is a 4.96 mi (7.98 km) long 3rd order tributary to Brokenstraw Creek.

[3] It is classed as a cold-water fishery by the Pennsylvania Fish and Boat Commission.

[5] According to the Geographic Names Information System, it has also been known historically as:[1] Gar Run rises on the divide between it and Oil Creek in Warren County, Pennsylvania about 2 miles east of Sanford, Pennsylvania and flows northeast to meet Brokenstraw Creek at Garland.

Gar Run drains 18.32 square miles (47.4 km2) of the Pennsylvania High Plateau province and is underlaid by the Venango Formation.

[6] The watershed receives an average of 42.6 in/year of precipitation and has a wetness index of 388.06.