Mile Marker Signs

Part of our series on road signs, Mile Markers are found on every Interstate, US highway, and State highway. You may find them on other roadways as well, usually only on access-controlled roadways.

Mile marker signs are very helpful for navigating the country, and are best used for figuring out distance from one point to another.

For the US Interstate system, Mile Markers start at 0 in the WEST or SOUTH, and INCREASE going EAST or NORTH. So if you’re traveling EAST on I-20, the mile marker numbers will be going up, but if you then turn SOUTH on I-35, the numbers will be going down. If you just remember that all miles start in San Diego (Southern California) and work their way up to Maine (Far North East USA) you’ll do fine.

A second key point to remember is that mile markers reset at every state line, no matter which direction you’re going. Heading West means the mile markers will tell you how long it is until the next state line (or end of the interstate), and the same is true if you’re headed South. Heading East or North means you’d have to know how many miles of interstate are in the state you’re in, but luckily that information is on the top of the page for each state in your Road Atlas, or readily available on google.

Alright, now that we know what they do, what can they tell us?
Well, for one thing, they can give us distance to exits! Exit ramps all over the US are numbered based on the Mile section they’re in. So, exit 44 should be 44 miles from the SOUTH or WEST state line of the interstate you’re on.

Something else they can do, especially for interstate travel, is help us plan our route for long trips. When I was driving commercial trucks all over the US, I always planned for a 600 mile day, so i’d crunch the numbers to figure out where that would get me to, and then look along that route for likely delays, detours, traffic, construction, weather, or other issues.

So next time you’re on the road, take a look at those mile marker signs, and start practicing the math to figure out miles from where you are, to where you want to be!