Slippery Rock Creek and the university in neighboring Butler County (
BU15) are named for an exceptionally slick rock six miles south of the mill near a Native American fording
On the west side of the mill site is a covered bridge of 1874 crossing Slippery Rock Creek. It is one of only three Howe truss bridges remaining in western Pennsylvania. Howe trusses were the first to use wood connected by iron rods, and were the forerunner of all iron truss bridges. Lawrence County's other covered bridge, a 121-foot Burr truss built in 1889, crosses the Neshannock Creek in Wilmington Township. Bridges are often associated with gristmills, as they provide critical access to the mill from both sides of the waterway.