Colonel William Byrd II proposed digging ditches and a channel through the Dismal Swamp in 1728, and construction of the Dismal Swamp Canal began in 1793 after the North Carolina and Virginia General Assemblies passed similar acts in 1787 for cutting a navigable canal. Linking the Chesapeake Bay and the Albemarle Sound, the canal provided a protected and efficient route for moving goods and people through the Great Dismal Swamp. Hired slave labor using primitive tools carried out the difficult work over twelve years in a challenging environment. In 1796, a French traveler and author reported that five miles of the canal had been completed in each state and that the number of locks needed was still unknown. By 1801, two locks had been built, a large one at the south end and a smaller temporary one several miles to the north. When first opened, the canal accommodated only flatboats and measured 15 feet wide and 2-3 feet deep. Tolls charged in 1807 depended on cargo weight, which mostly included shingles. George Washington, a landowner and investor in the Dismal Swamp Company, believed the swamp had no more than 1-2 feet of elevation difference, but the actual difference was ten feet, leading to construction of more locks in the middle of the canal around 1812. Built of square juniper timbers, these locks cost $300 each. Before major improvements, the canal had five raised levels and as many as nine locks, some privately built. Before 1826, the operational locks included Deep Creek, Wilkins, North West, Culpepper, Spences, and South Mills. Later improvements converted existing locks from wood to stone and removed two locks. Modern machinery reshaped the canal to a bottom width of 40 feet, a surface width of 60 feet, and a controlled depth of 6 feet. Tolls were removed, and management passed to the U.S. Army Corps of Engineers in 1929. New lift locks of steel and reinforced concrete were installed at the canal's only two locks, at Deep Creek, VA, and South Mills, NC, in 1940-1941. Today the 22-mile waterway serves as a historic recreational route and an alternate passage of the Atlantic Intracoastal Waterway.