The US Road System is one of the most celebrated public projects in the world, linking cities and states to each other. It involves millions of miles of roads and highways of varying lengths.
A vast majority of roads in the contiguous US are connected. That’s because the integrated road system consists of three categories of roads – routes, the Interstate Highway, and the State Highway. Hawaii and Alaska, which aren’t accessible via land roads, are outside of this network.
Keep reading to see how the American Road System makes virtually all the roads connected. We’ll also take a look at what led to the development of the road system in the US.
How are US Roads Connected?
US roads make up a network of roads and highways that reached 4,176,915.56 miles (6,722,094 kilometers) in 2019. This length makes the United States road network the world’s longest. The US is also home to many of the longest highways in the world.
According to government data, the US has a complete highway network that links virtually all population centers and counties. The interstate highway system is the link between all 48 states in the contiguous United States. That means if you start your road journey from a city in the east, you can reach the west and return to your starting point without leaving your car.
You can see the interconnected network of roads in this map outlining all the roadways inside the US.
However, this feature doesn’t include Alaska and Hawaii. If you want to get to Alaska by land, you need to drive through Canada. The state is 2,000 miles (3,218.69 km) away from Washington, the US state nearest to Alaska. Hawaii is also separate from the mainland US, so you can’t get there by road.
These limitations also include other islands that can’t be connected to the mainland via roads. For example, there’s a small island in Washington called Stehekin. This island isn’t reachable through roads, and you can only access it by ferry, private boats, and foot.
You may wonder what this network of roads consists of that allows it to be so interconnected. The secret lies within the three categories of roads that make up the US road system.
As a major component of the National Highway System, interstate highways are federally funded roads facilitating long-distance travel between states. Therefore, they provide support for defense, economy, and mobility, as the main purposes of the National Highway System. In terms of access, interstates have restricted access with almost no tolls, stop lights, and on/off ramps.
This system is the backbone of American transportation and provides routes for various transportation purposes, including traveling, commuting, and freight transport.
While the name may suggest these highways are only for traffic between states, that’s not true. The interstate system is designed to serve intra-state, interstate, and regional traffic equally. Many interstate routes, such as beltways and spurs, are entirely within a single state and don’t channel traffic outside the state.
You can also see auxiliary routes inside interstate highways, which normally have a three-digit number. interstate highways are recognizable through blue shield-shaped panels with their number written on them in white, and above them, you can see the word “Interstate.”
The longest interstate highway in the US is Interstate 90, connecting Seattle in the east to Boston in the west. This highway runs for 3,020.44 miles (4,860.93 km).
A vast majority of highway mileage belongs to rural areas, with over 3 million miles. However, they don’t carry all that much traffic. Urban highways carry 60% of the traffic.
You’ve surely heard of Route 66, the most iconic US highway constructed in 1926.
If you ever want to go to a small city or a ghost town in the US, this route will take you there. Routes (numbered highways) are the older types of roads that connect cities. They later transformed into the more modern category, Interstate Highways.
Routes are toll-free and numbered in an interesting order. The roads running north-south have odd numbers, and those running east-west are even-numbered. These numbers grow in value from west to east and south to north.
You can recognize them as white panels with the route number on them. Since these roads are older than the other three, they’re less maintained and offer a lower comfort level.
Local governments and states are responsible for maintaining the US routes, and they are coordinated by the American Association of State Highway and Transportation Officials (AASHTO).
However, the Interstate System has replaced routes in most areas. But in places where the Interstate System hasn’t developed, regional and intrastate traffic officials maintain the safety of the routes.
US State Highways can be either primary or secondary roads that belong to each state’s highway system. They’re also of varying capacities and qualities depending on the traffic. Some of the most heavily traveled state highways have interstate standards and qualities.
The panels that indicate these highways are different in shape and color. Each state has its specific design based on the state’s geographic shape. But the default state highway marker is in the shape of a circular shield.
The three categories of roads mentioned above have made the interconnected network of American roads possible. So, if you want to travel from point A to B and back without interruption, you can use a combination of these roads and highways to complete your journey.
Highway systems also have their specific hierarchies, consisting of different categories of roads. They include:
- Local roads. They connect homes, businesses, and small communities.
- Collector ways. They serve as connectors between towns and larger roads.
- Arterial roads. They provide transportation channels between towns and cities.
These are also parts of the integrated highway system that connects all cities and towns.
The Development of the Interstate Highway System
During the 1910s and 1920s, when Americans started to use cars extensively, roads called “auto trails” were the only transportation paths. Private organizations and individuals were primarily responsible for their construction.
When cars grew in number, road safety became a concern. So, the AASHTO proposed to the government to step in and build roads of higher quality. In 1926, route 66 was built to connect Chicago to Los Angeles. It was the Main Street of America until the new federal highway system came along.
While the history of numbered highways dates back to the 1920s, the interstate system dates to the post-war era.
Many sources have mentioned President Eisenhower as the person who conceived the idea of an interstate system. However, the Bureau of Public Roads had already described what would become the interstate system in it a report to Congress in 1939.
President Eisenhower supported the enactment of the act that funded and built the project. The Federal-Aid Highway Act of 1956 was enacted to respond to the needs of a growing post-war population. These needs were mostly economic, highway safety, and traffic-related.
These highways became popular because they had fewer stopping points, more lanes, and higher speed limits than the older routes.
The developers of the interstate highway system aimed to make an integrated grid of roads that linked all cities and major population centers.
The three types of roads available in the US help make all the roads interconnected. That means when you start your journey from your home, you can use a combination of these three roads to reach your destination and go back.
However, it should be noted that Alaska, Hawaii, and certain far-flung places in the conterminous US like Stehekin are not connected by the US road system.
- Britannica: Route 66
- Britannica: Roads and highways
- Federal Highway Administration: Interstate Highway System – The Myths
- Difference Between: Difference Between Interstate and Highway
- Route 66 Tours: The U.S. Highway and Interstate Highway System: What’s the Difference?
- Lazy Trips: Can You Drive To Hawaii From Mainland United States?
- Road Traffic Technology: The world’s biggest road networks
- ARTBA: Highways Policy
- Bureau of Transportation Statistics: System Kilometers Within the United States
- Federal Highway Administration: Part VII – Miscellaneous Interstate Facts – Engineering Data
- AASHTO: Homepage
- National Park Service: Stehekin – North Cascades National Park (U.S. National Park Service)
- Federal Highway Administration: Office of Highway Policy Information
- Statista: Length of the largest road networks