Mile markers started as simple reference points. So, why do we still see them on our highways today? Hasn’t GPS overshadowed these simplistic markers?
Read on to find out.
A bit of history
Mile markers began as humble little posts or stones placed along roadways. They told travelers how far they were from a fixed starting point.
The practice of using mile markers goes way back. The Romans carved milestones to mark distances along their roads. The idea stuck.
In the U.S., modern mileposts became standardized with the development of the numbered highway and interstate systems. Mileposts on interstates begin at the route’s most southerly or westerly point and increase as you travel north or east. That’s why exit numbers often match mile numbers.
Old-school and outdated?
Today, GPS units and smartphone maps show your exact coordinates and ETA, so why do we need the old-school, green mile sign? Few drivers today express their location using mile markers. Instead, they read their navigation app’s blue dot.
In busy metro corridors, mileposts are less visible or even omitted. Some state and county marker systems vary. This confuses travelers and seems unnecessary, as well.
Do RVers still need mile markers?
But wait! Even if you barely glance at them, mile markers perform several practical jobs that matter to RVers.
• Accurate location for emergencies and help. If your rig breaks down, referencing a precise milepost to give to highway patrol, tow services, or 911 dispatchers speeds response. This, in turn, reduces the time you (and your pets) are exposed on the road’s shoulder.
• Exit planning and mileage math. Unlike some route names or exit lists, mile markers let you quickly calculate remaining distance between services: “rest area at mile 185, fuel at 203” becomes easy arithmetic on the highway. That helps when you’re towing, assessing safe pull-over distances, or planning fuel stops for rigs with limited range.
• Maintenance, construction, and reporting. When you call to report a road hazard (e.g., accident, downed tree, debris on the road), transportation agencies log incidents by milepost number. Contractors working on a job are handed milepost ranges for where work must be done. For RVers following detour instructions or official bulletins, a mile-based description is precise and universal.
• Legal cases. Interstate mileposts are the backbone of many legal references, as well. Crash reports, maintenance records, and right-of-way descriptions often use mile markers. That makes them useful for anyone needing documentation after an incident.
“Rule breakers”
California stands apart from other states because it does not follow the traditional mile marker system. Instead, it uses what’s known as a postmile system. These markers track how far a highway runs within each individual county rather than measuring mileage across the entire state.
A few other states (Nevada, Ohio, and Tennessee) also use county-based reference markers on certain non-interstate roads. However, when it comes to interstate highways, they follow the standard statewide milepost numbering system.
Why the system still works
States have modernized how they place markers. Some add fractional reference markers between whole-mile posts. Others tie markers to county boundaries, and a few use supplemental reference plaques for ramps or specific points.
The mile marker system’s flexibility has kept it relevant. It integrates with digital mapping, informs exit numbering, and provides an official “common language” across agencies.
Practical tips while RVing
Keep an eye out for the next marker when you pass services and note the mile before you pull off. It will make calling for help or finding your campsite easier.
When you cross state lines, remember that the mile marker numbers reset or shift depending on state rules. Double-check if you’re relying on mile points for trip planning.
If you’re in an area where mile markers are sparse, note nearby exit numbers, bridges, or mile-fraction markers.
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RVT1249
We rely on mile markers a lot when traveling. I keep a journal of good fuel stops, rest areas and good camping spots and make a note of their exit (or mile markers) number.
And most fuel stops on interstates show the route # and mile markers on their website to pinpoint their locations.
I had a flat on my RV about 2 years ago just south of Henderson, NV. and I was at a mile marker, helpful? Nope. The road service I called and told the rep the hwy and mile marker. After 2 hours a rep called back and said they can’t find us. They sent the tow looking in the opposite side of the state? Finally after about 4 different phone reps we got one that was familiar with the area and sent the tow driver to our RV. Now if that happens I know to tell them I am so many miles south of that city instead of a mile marker.
Strange. Mile markers are the same place no matter what direction you are going. One direction starts low and the other direction starts high. The same mile marker is in the same place.
Mile markers are especially useful when we are looking for a specific exit. Exit 13B is at mile marker 13. However, someone in our “use it or lose it” budget department has now added mile markers at the half mile mark. And to add to the waste the signs read top to bottom. Mile marker 13.5 reads top line 1, next line 3., bottom line 5.
One of the best travel guides you can buy that covers mile markers, mile posts, etc is NEXT EXIT. It gives you every exit by mile reference and tells you what services are available at that exit. It comes out new every year but old ones work well too, as exits almost never change and services seem to stay constant.
There is also a version of NEXT EXIT called iExit. that you can put on your smart phone that in addition to the exit information can pinpoint your location. Very useful for interstate highway travel and more up to date than the printed version.
If you use I-10 across Florida Panhandle, know your mile marker. Since it is largly very rural, this is the only clue that you can provide for emergency services.
I use the mile markers for telling people which freeway exit to get off on to get to our house. I also look at them when traveling in our state to know how far away I am from our next exit or destination exit. When traveling the length of California I know when we are close to our home state of Oregon. I do the driving so I really am looking at the road and not the map gps on our screen.
It is important to note the mile marker – but it is critical to report your direction of travel and the hiway you are on! Guess it wouldn’t matter which direction if you were half way between both borders! i.e., In the middle of the state.