Source: United States Department of Transportation – Federal Highway Administration, Painting by Carl Rakeman.
The macadam road construction principle permitted the first modern all-weather hard surface roads. The above painting shows the process being applied to build the first macadam surface road in the United States in 1823. It linked Hagerstown and Boonsboro, Maryland. The road was composed of three layers of compacted rocks, with the top layer cemented with water to create a concrete-like surface. A curved road surface insured drainage with runoff water accumulating in side ditches.