An Act of Congress in 1806 authorizing construction of the National Road required mile markers at regular intervals to reassure travelers that they were on the correct route and to show distance traveled and distance to destinations. The use of mile markers began in the Roman Empire with stone obelisks, and the first Roman examples appeared in the fourth century B.C. on the Appian Way from Rome to Brindisi. Along the National Road, markers were set one mile apart on the north side of the road. Each state used a different design but displayed the same information. In Ohio, the markers were square with round heads and made of an early form of concrete, sandstone, or limestone, while in Pennsylvania they were obelisks made of cast iron. Ohio’s five-foot-tall markers were set two feet into the ground with three feet exposed. Each marker gave the distance from Cumberland, Maryland, where the road begins, and the names and mileage of the nearest cities and villages for eastbound and westbound travelers. The top showed the number of miles from Cumberland, the next row gave the next big town and its distance, the left side named the next big town to the east, and the right side named the next big town to the west with the miles remaining. The lowest level usually showed an initial and a small number indicating the nearest town, recognizable to local people. By the 1920’s, a uniform highway numbering system and standardized road signs had replaced the old mile markers, though many remained along the road.