County Bridge No. 171

County Bridge No. 171 is a historic stone arch bridge located in Tredyffrin Township, Chester County, Pennsylvania. It spans Valley Creek. It has three spans; the main span is 25 feet long and flanked by two 15-feet long spans. The bridge was constructed in 1907, of coursed rubble with brick arch rings and a contrasting parapet.

It was listed on the National Register of Historic Places in 1988.