A bunch of years ago, our family traveled around the United States as nomads for a year, driving thousands of miles through dozens of states. And throughout the entirety of that kind of epic road trip, I never once learned that there’s a system for how our highways are numbered. It always seemed random, but it’s so very not.
A viral Facebook post sharing just two basic principles of interstate highway numbering blew my mind, and also the minds of approximately 196,000 other people who shared the post in the past few days. Rich Evans included two images showing the East-West interstate highways and the North-South interstate highways with this explanation:
“I always knew there was a logic to it, but I never saw it explained so well until I stumbled upon this delightfully informative short video on how the US interstates are numbered.
Those with 2-digits traverse the entire country.
If they end in “0” they run East-West (10, 20, 30, ..)
If they end in “5” they run North-South (5, 15, 25, ..)
Those with 3-digits are bypasses and contain the last 2 digits of the interstates they bypass.
That’s it! (plus exceptions 
) Neat!”
It is neat, actually. But it’s even a bit more complex than that, and the video link Evans shared explains it all in a clear (usually) and funny way. “The Interstate’s Forgotten Code” from CGP Grey uses animation to show that the numbering system does indeed have a rhyme and reason, despite there being a few notable exceptions. (A highway system would be boring if it always followed the rules, wouldn’t it?)
Enjoy learning something new if you didn’t already know this:
Source: https://www.upworthy.com/how-us-highways-are-named
