• Carrie Crocker

The Origin of the US Highway Mile Marker

Updated: Apr 21

All Roads Used to Lead to Rome

Ever wonder what those green signs with numbers on them are next to the road on the US highway? Well they actually have a purpose. Those green signs are called mile markers, or route markers, are in place to countdown the distance to and from a destination as you travel along the highway. Another reason for those signs today are for reference to use for emergency services if you are broken down on the side of the road. But how was a US Highway mile marker created in the first place?

US Highway Mile Marker on interstate

The human race used to be predominately nomadic. We traveled across stretches of land to reach different places to obtain water and food for survival. We traveled and found spots rich with resources causing us to develop shelters, farming spots, and we became settlers. With the development of agriculture and construction we began to create stronger shelters and larger settlements. During this time in our settlements we developed clothing and textiles, made tools and weapons, created languages, harvested spices, developed currency, and more.

But these developments of goods and tools that helped form our civilizations couldn't develop in neighboring settlements unless we continued to travel to and from each settlement. We interacted and shared these findings with other humans. We walked on foot flattening the land and clearing vegetation out of our way with our hands and with tools to make pathways and trails. These pathways and trails that were cleared between settlements became what is known as trade routes, and as we traveled we began to invent new ways of improving routes by laying stones. The first sign of laying a stone on a pathway known as a street paving has been found from around 4000 BC in cities of the Indus Valley Civilization.

Trade routes strengthened in use with the development of using horses and donkeys as pack animals to carry the goods for us. With supply and demand for these good and services and the invention of the wheel we created carts so we could transport larger quantities. The first simple two-wheel cart appears to have been used in Mesopotamia and northern Iran in about 3000 BC. These carts evolved into two-wheel chariots appearing in about 2800 BC.

The chariot was a fast, light, open, conveyance drawn by two or more horses that were hitched side by side, and was little more than a floor with a waist-high guard at the front and sides. It was initially used for ancient warfare during the Bronze and Iron Ages, but also used for travel and transport.

Illustration of roman chariot

One of the largest and most powerful civilizations in time that employed the chariot was the Roman Empire. Rome professionalized and expanded its military and created a system of government called res publica in 509–27 BC. With the advent of the Roman Republic, there was a need for armies to be able to travel quickly from one area to another, and the roads that existed were often muddy, which greatly delayed the movement of large masses of troops. To solve this problem, the Romans built great roads. These Roman roads used deep roadbeds of crushed stone as an underlying layer to ensure that they kept dry, as the water would flow out from the crushed stone, instead of becoming mud in clay soils. The legions made good time on these roads and some are still used millennia later.

The earliest and most strategic Roman road was the Appian Way (or via Appia). The Appian Way connected Rome to Brinidisi, in southeast Italy, and was known as "the queen of the long roads." Named after Appius Claudius Caecus, the Roman censor who began and completed the first section of the Roman military roads in 312 BC.

Roman mile marker

(Photo: Júlio Reis/WikiCommons CC BY-SA 3.0)

The modern word mile derives from the Latin milia passuum, "one thousand paces", or in total 1,476 m (4,843 ft). On the Appian Way is where the first milestones were erected before 250 BC. A milestone, or miliarium, was a circular column on a solid rectangular base, set for more than 2 feet (0.61 metres) into the ground, standing 5 feet (1.5 metres) tall, 20 inches (51 centimetres) in diameter, and weighing more than 2 tons. At the base was inscribed the number of the mile relative to the road it was on in distance from the city of Rome, the Roman Republic, and later known as the Roman Empire's capital city.

Fast forward to today where chariots have become automobiles and what we have now for the US highway systems for a milestone is the mile marker. These mile markers show the number of miles from where the Interstate route entered the state in which you are traveling. The counting always begins at the state line in the south (for north-south routes) and in the west (for east-west routes). So, mile marker numbers always get larger as you travel east or north. From the beginning of the US Highway Interstate system most Interstate highways have markers every mile.

US Highway route marker

So when you are driving your chariot down the road on your next road trip, give thanks to the Romans for creating the first mile marker to help guide your way. And if you are in need of Mile Marker's for your next road project call us for a free estimate.

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