Laurel's earliest mill stood on land originally inhabited by Native Americans, with early mills built on the banks of the Patuxent River at the fall line, where changing elevation provided water power. A massive dam built in 1850 controlled the river's flow to supply the Laurel Cotton Mill, and newspaper reports in 1855 gave its dimensions as 222 feet wide and 27 feet tall. On the south bank, a canal called the mill race ran about 600 feet and directed water into the mill, while wooden doors in a large sluice gate across the channel controlled the flow according to the power needed. Water moved from the race or canal to the mill, where it powered two overshot wheels and later a large Boyden Turbine before returning to the river. The dam required frequent repairs, and diary entries by Laurel Mills Superintendent George Nye in June and July 1879 recorded low water, repeated leaks, and a shutdown for repairs until the 21st. Most of the dam was blown up in the 1940s.