Lock #9 at Lapidum was one of 29 numbered locks on the 45-mile-long Susquehanna & Tidewater Canal, a major route for commerce between central Pennsylvania and the Chesapeake Bay from 1839 until 1894. The locks raised canal barges in a series of steps from tidewater Havre de Grace, Md. to an elevation of 231 feet at Wrightsville, Pa., and an outlet lock built in 1844 connected the canal with the river. Constructed of large blocks of locally quarried stone, Lock #9 had a chamber approximately 170 feet long and 16 1/2 feet wide, lined with wood planking, and its length allowed two canal barges to be raised or lowered at the same time. Barges traveling upstream were pulled into the lock, the gates were closed, and water entered through sluice valves, or "wickets," in the upper lock gates, raising the water and the barges to the next canal level; for downstream barges, the process was reversed.