Interstate Numbering System and How to Decode it
You probably know the roads pretty well in the area where you live, but when you head out to unfamiliar territory, highway and other route signs become more important. Most people don't know that many highway, road marker and exit signs contain useful information other than just their number. Signs are communicating with you, to let you know where you are at all times. Knowing what the numbers on Interstate signs have to tell you can be a great aid to navigation.
The Interstate Numbering System is an important part of the American highway system. It was created in 1956 to provide a uniform way for numbering highways across the United States. It is a system of numbered routes that currently spans 41,000 miles and includes the US Interstate Highways, US numbered highways, and other highways that are part of the American Association of State Highway and Transportation Officials’ (AASHTO) approved systems of highways.
The Interstate Numbering System is designed to be easy to understand and navigate. Each route is assigned a number, which indicates the type of highway, the direction of the route, and the location within the United States. The Interstate Numbering System consists of three main categories: even numbers (such as I-10), odd numbers (such as I-5), and three-digit routes (such as I-95).
The first two digits of the Interstate Numbering System indicate the type of route. Even numbered routes are generally east-west routes, while odd numbered routes are typically north-south routes. The last two digits indicate the location of the route within the United States. For instance, I-95 runs along the east coast from Maine to Florida, while I-75 runs from Michigan to Florida.
The three-digit routes are unique because they are not part of the main Interstate Numbering System. Instead, these are auxiliary routes that supplement the main highway system. They are identified by a prefix that indicates the region or state where the route is located. For example, I-495 is an auxiliary route in the Washington, DC area.
Once you know the basics of the Interstate Numbering System, it is easy to decode the routes. For example, I-10 is an east-west route that runs from California to Florida. I-5 runs north-south from Washington to California. I-95 runs along the east coast from Maine to Florida. I-75 runs from Michigan to Florida. And I-495 is an auxiliary route in the Washington, DC area.
The Interstate Numbering System is an important part of the highway system in the United States. It provides a consistent way to number highways, making it easier to navigate the country. Understanding how to decode the routes is the first step in becoming familiar with the system.