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

These days, finding your way from place to place in the States is crazy easy. Type an address into your car's GPS or a smartphone, and let a computer-generated voice guide you at every turn. Even in the old days before satellite tracking, road maps and a compass kept travelers on track. However, there's a simple numerical code found in most US highway designations that can also guide travelers, albeit on a very basic level.

Older readers likely know this, but for the younger adventurers, the US Numbered Highway System established a framework for naming highways. It's not just a random series of numbers – roads running east and west are even-numbered, with north-south roads being odd. As such, if you're seriously lost and find yourself on Interstate 70, you can at least take comfort in knowing you're either headed towards the East Coast, or West Coast. Likewise, if you're on Interstate 75, cool northern states or warm southern states are coming your way.

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Of course, that still leaves lots of space to cover but the numbering system addresses location as well as direction. Even numbers represent east-west highways, but the further south you go, the lower the number. For example, Interstate 10 skirts the southern regions of the US, whereas Interstate 90 runs through the Northern Plains all the way to Seattle. The same holds true for north-south roads, starting with low numbers in the west. Interstate 5 follows the West Coast from Canada to Mexico, and on the other side of the continent, Interstate 95 brushes the Atlantic Ocean from Canada to Miami.

The video from CGP Grey at the top of the article offers an amusing look at the naming structure, and yes, there are some exceptions to the rule. We touched on major interstate highways established in the Federal Aid Highway Act of 1956, but when you look closer at state and even county roads, you'll often find the same structure. After all, it's hard to find a road further west in the continental United States than California Route 1. However, North Dakota Highway 5 is practically in Canada, and it runs east-west. So yeah, the system isn't perfect.

Still, it's neat to see some patterns in the chaos.