3,980,817 miles

InTrans / Nov 01, 2017

Go! Magazine

posted on November 1, 2017

The United States has a lot of roads—3,980,817 miles to be exact.

Roads are relatively simple but make a big impact, and they exist nearly everywhere, guiding traffic and travelers from one side of the country to the other. But it didn’t happen all at once. And the “first roads” definitely didn’t look like the roads we use today.

Usually paved with asphalt or concrete, our roads today are relatively smooth, sturdy, and durable. Some roads even support millions of vehicles per day. But the first roads—not just in America but in the world—were a little more simple, although important all the same.

A history of roads

In the Paleolithic period, which spanned from about 2.6 million to 10,000 years ago, humans didn’t need to construct roads, they instead followed game trails of the prey they hunted. Other early developments in road building included clearing trees and stones from these paths.

As humans began buying and selling from one another more, these early “roads,” or dirt tracks, were widened and flattened to accommodate more human and animal traffic. Some of these roads made up fairly extensive transportation networks, opening up more possibilities for communication, trade, and governance.

Gravel road. Photo from Wikipedia via Repat

Roads with even wider paths and smoother terrain were required as pack animals and other early modes of transportation were developed. The first vehicle—the travois (i.e., a sled invented around 5000 BCE)—along with pack animals were used to haul people and agriculture.

Then, with the invention of the wheel and wheeled-based transport, roads had to improve yet again. The natural surfaces that had been used as roads in the past were too weak to support wheeled vehicles, especially when wet, and urban areas began constructing stone-paved roads instead. Over the next few thousand years, roads would develop into what we know today!

Paving the way

There are over 2,605,331 miles of paved road in the United States. In the past, roadways were made up of materials like gravel, cobblestone, and other naturally-sourced materials. Today, most of these surfaces have been replaced or paved over with asphalt, concrete, or some other type of pavement.

That said, there is still 1,375,486 miles of unpaved road across the country. These roads are usually “paved” with naturally-sourced materials like gravel or cobblestone. You can find this type of road in more rural or agricultural areas, whereas you’ll almost always find asphalt/concrete roads in urban or city areas.

Asphalt concrete has been widely used to pave roads since the 1920s. Most asphalt surfaces start with a gravel base and then have asphalt applied at a hot, warm, or cool temperature. The advantage of using asphalt to pave roads is that it’s relatively low noise, low cost, and generally easy to repair.

Then there are concrete road surfaces. Concrete is made using cement, coarse aggregate, sand, and water. The material is applied when it is freshly mixed together. The advantage of concrete-paved roads is that they are typically stronger and more durable than asphalt. Concrete road surfaces can also be grooved to provide “a durable, skid-resistant surface.”

The road ahead

Although these materials have advantages, asphalt or concrete materials also come with a list of disadvantages. Asphalt roads aren’t as durable as other pavement methods and can become slick and soft in hot weather. Concrete has an initially high cost of construction, and construction can furthermore be time consuming.

Someday, something will probably replace asphalt and concrete roads the same way gravel and cobblestone roads were replaced. So, the real question is now: What could our roads look like in the future? What will the next big step for roads be?

In the future, we might come up with a better way to pave roads or an entirely new material to construct them with! For example, in the Netherlands there is a company called VolkerWessels building a road made of 100 percent recycled material called the PlasticRoad. The company claims it is “the ideal sustainable alternative to conventional road structures.”

If the future of the roads we drive were in your hands, how would you engineer it? Could we build roads from recycled materials, up in the sky, or underground? Maybe instead of roads, we’ll have tunnels, something like the proposed Hyperloop. Considering how far we’ve come to get where we are today, anything seems possible.