Can You Read the Washington State Interstate Highway Secret Code?

In today's Google Maps world, a long-lost code Interstate Highway system has been lost to time. Let's see if you can recall the one code that everyone knew back in the day.

Can You Read An Interstate Roadway System?

It's one of those things that I'm sure most drivers have forgotten because of technology but do you remember how the interstate highway system works?

Get our free mobile app

It's almost like a long-lost code that only the Mayans remember but it's something we all learned in school or did we? I've long forgotten but I'm sure we talked about the interstate highway in school and how the numbering of the highway works.

What Is The Numbering Of Washington's Interstate Highway System?

I've included a video below illustrating how the numbering works on the Washington State Interstate Highway.

Why is it I-5? There's a reason and here's how it works:

It's pretty informative don't you think? Interstate Highway's numbering system was designed in 1957 and according to Wikipedia, here's how the numbering system works:

While numerous exceptions do exist, there is a general scheme for numbering Interstates.

Primary Interstates are assigned one- or two-digit numbers, while shorter routes (such as spurs, loops, and short connecting roads) are assigned three-digit numbers where the last two digits match the parent route (thus, I-294 is a loop that connects at both ends to I-94, while I-787 is a short spur route attached to I-87).

In the numbering scheme for the primary routes, east-west highways are assigned even numbers and north-south highways are assigned odd numbers. Odd route numbers increase from west to east, and even-numbered routes increase from south to north (to avoid confusion with the U.S. Highways, which increase from east to west and north to south).

This numbering system usually holds true even if the local direction of the route does not match the compass directions. Numbers divisible by five are intended to be major arteries among the primary routes, carrying traffic long distances.

Primary north-south Interstates increase in number from I-5 between Canada and Mexico along the West Coast to I‑95 between Canada and Miami, Florida along the East Coast.

Major west-east arterial Interstates increase in number from I-10 between Santa Monica, California, and Jacksonville, Florida, to I-90 between Seattle, Washington, and Boston, Massachusetts, with two exceptions.

There are no I-50 and I-60, as routes with those numbers would likely pass through states that currently have U.S. Highways with the same numbers, which is generally disallowed under highway administration guidelines.

It's fascinating how the interstate highway system works and now you know why I-5 exists on the west coast while I-90 is on the east coast.

It's one of those code systems we've long forgotten because of Google Maps and Google but always fun to revisit for a refresher or if you are ever going to be on Jeopardy!

You can read more details on the interstate highway system here or click on the video above