Numbers Used for The US Interstate Highway System Actually Have A Code

These days, finding your way from one place to another in America is very easy. Type the address into your car’s GPS or smartphone, and let a computer-generated voice guide you at every turn. Even in the days before satellite tracking, road maps and compasses kept travelers on track. However, there is a simple numeric code found on most US highway signs that can also guide travelers, though on very basic level.

Older readers may know this, but for younger adventurers, the US Numbered Highway System created a framework for naming highways. It’s not just a random string of numbers – roads running east and west are numbered even, with north-south roads odd. That way, if you do get really lost and find yourself on Interstate 70, you can at least feel comfortable knowing you’re heading for the East Coast, or the West Coast. Likewise, if you’re on Interstate 75, a cool northern state or a warm southern state will come your way.

Of course, it still remains many space to cover but the location address numbering system as well as directions. An even number represents an east-west highway, but the further south, the lower the number. For example, Interstate 10 circles the southern United States, while Interstate 90 crosses the North Plains all the way to Seattle. The same goes for north-south roads, starting with a few to the west. Interstate 5 follows the West Coast from Canada to Mexico, and on the other side of the continent, Interstate 95 sweeps the Atlantic Ocean from Canada to Miami.

Video from CGP Gray at the top of the article offers a cute look at the naming structure, and yes, there are some exceptions to the rule. We touched on the major interstate highways defined in the Federal Highway Assistance Act of 1956, but when you take a closer look at state roads and even county roads, you’ll often find the same structure. After all, it’s harder to find your way further west in the continental United States than California Route 1. However, North Dakota Highway 5 is practically in Canada, and runs east to west. So yeah, the system isn’t perfect.

However, it’s neat to see some patterns in the mess.