When you travel in the US, you may notice numbers that are placed on highway signs. Do you know why these numbers are odd or even and what they really mean? This is basically the US Highway numbering system, which is not selected randomly.
So, you need to know which pattern these numbers follow and what directions they show you. Today, you will learn all about the US highway numbering system and how it works.
US Highway System History
In the past, highways in the United States had a name system instead of numbers. Some roads were very popular at that time, such as “Lincoln Highway” or “Dixie Highway”. But people get confused because these roads have different names in different locations. To fix this problem, a group of engineers decided to change the system in 1925.
At that time, they gave a specific number to each US highway. This pattern was simple and easy to follow for road users. However, the highway numbering system was officially registered in 1926. Basically, the group behind this plan was called AASHO (American Association of State Highway Officials).
They also worked with the federal government. After a long process, a pacific number was assigned to each USA highway. In 1926, the America Highway Numbering System officially started. It was simple and easy to follow for you. For example, when you know the number of roads, you can tell where it will end.
Highway Numbering System US
The USA highway numbering system is actually a set of regulations. Based on this pattern, different highways have a unique number. When you drive on American routes, these numbers help you to know your road’s direction and its location.
1. East-West Routes
East-west highways are parallel to one another across the country. These roads help you travel from the East Coast to the West Coast. You can identify them with all even numbers, which are used for east-west routes in the US. For example: the U.S. Highway 10 and US Highway 60 are both east-west roads.
If you are driving your car on a road such as I-40 or I-90, that means you are on the way from east to west. In such a way, you can easily identify your direction very well. This overall system helps you to plan where you can stop for fuel or rest.
2. North-South Routes
Odd number road systems such as I-5 or I-95 inform you that you are on north to south routes. However, you will see the smallest number will start on the west side of the country. As you move your vehicle to the east, you will see the number will also increase.
For example, America highway 1 is near the East Coast. But, highway 101 is in the western part of the country (near the Pacific Ocean). It helps you travel up and down the country. These roads connect locations from the top of the United States to the bottom.
How American Highway Numbering System Works?
Odd vs. Even Numbers
Highways use odd and even numbers to show you the right direction. For instance: if you want to ride north or south, you must use highway 5. On the other side, If you see highway 40, it means you are on side to side travel. In short:
- Odd numbers for north and south direction.
- Even numbers indicate east and west.
One- and Two-Digit Highways
In America, the majority of highways have one & two digit systems like US 1 or US 66. Generally, these routes are long and also link many states together. Keep in mind, if you see a few digits, it tells you that the road is more important.
Additionally, one digit highways direct you about major routes. But, two digit highways may not be as long as one digits. However, you can still cover a pretty good distance.
US Highway Numbers By Location
USA highway numbers also follow a location pattern. You will see small numbers in the top right of the country. Further, you will observe a big route number in the bottom left.
How are State Highways Numbered
You should remember that each state follows their own system and standard for numbering highways. So, we can say that the system can be changed based on every state law.
In the case of America, they follow a clear pattern. Odd digits (smaller numbers) used for north and south but even (bigger numbers) for east & west.
U.S. Highway Sign/U.S. Highway Symbols
You can easily spot signs on US highways. They basically help you to know how you can drive safely on American routes. You will see a white shield with a black border as well.
Inside the shield, you will also observe a highway number in black text. No matter where you are, you can recognize these signs because all signs are the same across the country. Mostly, you will find signs on USA roads, at exit and on highway maps too.
US Highway vs Interstate Highway
Below is the difference table of American highways & interstate highways.
| Main points | US Highway | Interstate Highway |
| Start Year | 1920s | 1950s |
| غاية | Connect cities & towns | Built for fast and long-distance travel |
| Speed | Slower | Faster |
| Toll Road | No Tolls | Have Tolls |
| Managed by | State & Federal Government | Mainly Federal Government |
Angular Auxiliary Routes: 3 Digit Highways
You will see, some highways have three digits instead of one or two. These are actually called auxiliary routes. Its main purpose is to make connections to main highways. So that, you can travel to more places.
Loops and Beltways
Loops and beltways are highways that are made around big cities. With their help, you can avoid traffic in the center of the city. They follow 3 digit systems such as I-285 & I-610.
Spur Routes
When you don’t want to travel on the main highway, you can use spur routes . Because, these are small roads which are made in the middle of the city. Spur routes follow a 3-Number pattern which starts from an odd digit.
Interstate Exit Numbers
These numbers inform you about where your current path will end (direction & location). Each number will show you numbers of miles you have traveled. For example: If you see Exit 25, that means you are 25 miles from where the highway started.
How are Interstate Highways Numbered?
- Odd numbers show routes of north and south. While even digits go east & west.
- Smaller numbers start in the south/west (get bigger as you move north and east).
Longest Interstate in US
If we talk about the longest interstate in the USA, it is Interstate 90 (I-90). This path starts in Seattle and ends in Boston. That means you can go across the whole country when you drive on it. Further, the road is more than 3000 miles long and you can travel through 13 states as well.
Conclusion of American Highway System
To sum up, we can say that highway numbers in US are based on a systematic process. You can see how these road numbers help you to find your way in the United States. You can also notice that odd or even & big or small, each digit tells you something.
So next time you drive in this country, you must look at the signs. They will guide you, save your time and make your trip a lot easier.
