in 18th century America. Crews consisted of unskilled laborers, skilled indentured servants, and slaves rented from nearby plantations. The work was difficult and dangerous. With one of the earliest uses in this country of black-powder blasting, workers forced a channel through the rock cliffs for the final three locks. The canal is 1,820 yards long and was completed in 1801, and opened to traffic in 1802. Its five locks raised or lowered boats to skirt around Great Falls, and were constructed of red sandstone from the Seneca Quarry across the river in Maryland. Locking through the whole canal could be accomplished in about an hour. An entire town grew up around the construction site to serve as headquarters for the Patowmack Company and home for the workers. The town was named Matildaville by its founder, the Revolutionary War hero Light Horse Harry Lee. Harry Lee, the father of Robert E. Lee, named the town for his first wife, Matilda Lee. Seneca Falls Canal This canal was 1,320 yards long and despite going down 7 feet, had no locks, and is on the Virginia side. This was worked on in 1785. This refers to the falls which start just below Seneca Creek, Maryland (this is not to be confused with Seneca Falls, New York where the Cayuga–Seneca Canal was built). It is opposite Dam No. 2 / Violettes Lock on the C&O Canal. Shenandoah or Paynes Falls Canal This canal, just below Harpers Ferry, was 1,760 yards long, dropped 15 feet, and had no locks either. This was also called the Bullring Canal by some boatmen (the falls also being called "Bullring Falls" according to Thomas Moore's 1820 writings), and was made up of two short skirting canals with a "short sheet of water about a quarter mile" between them. Note: There is a good deal of confusion, even in the Potomac Company Records, to the canals around Harpers Ferry, more than one being called the "Shenandoah Canal" (sometimes inaccurately). House Falls Canal This Maryland canal, also called the Long Canal, had no locks, and overcame a drop of three feet. This canal was reused for the C&O Canal, between Dam No. 3 and Lock 34 (Goodheart's Lock), according to a 1922 survey, for a distance of almost a mile. Other improvements Some other tributaries to the Potomac had work done on them, such as Conococheague Creek, the Monocacy River, Patterson