Making Sense of the Interstate Highway System

Happy Friday, everyone. I prefer to travel via Amtrak and intercity rail, but from my flat I can see two routes of the US interstate highway system: I-676 and I-76. And when I drive to my hometown outside Philadelphia, I use those two routes. Plus, I live not far from I-95, the main highway corridor running through the East Coast of the United States.

But what a lot of people do not know is that the numbering system for US interstate highways—by and large—has an underlying principle. (I say by and large because I frequently drive on one of the most infamous exceptions.) Thankfully, the YouTuber CCP Grey just released a video that details the numbering system.

The north-to-south routes

And if you’re curious about that exception, which runs through Altoona, Pennsylvania, here’s a screenshot. But you should watch the full video.

I-99? You can thank a congressman for that one.

Credit for the piece goes to CCP Grey.

Author: Brendan Barry

I am a graphic designer who focuses on information design. Most recently I worked for the Economic Research Department of the Federal Reserve Bank of Philadelphia and prior to that I was Head of Design at Euromonitor International with my design team split between Chicago and London.

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