Andrews Run is a long 3rd order tributary to Brokenstraw Creek. It is classed as a cold water fishery by the Pennsylvania Fish and Boat Commission.
Andrews Run is formed at the confluence of Birch Springs Run and Rattlesnake Run in Warren County, Pennsylvania about 3 miles south-southeast of Pittsfield, Pennsylvania. It then flows northeast to meet Brokenstraw Creek at Pittsfield, Pennsylvania.
Andrews Run drains of the Pennsylvania High Plateau province and is underlaid by the Venango Formation, Corry Sandstone through Riceville Formation and the Shenango through Cuyahoga Group. The watershed receives an average of 43.1 in/year of precipitation and has a wetness index of 389.62. The watershed is about 79% forested.