MileCheckDriving in the US as a foreign visitor: what nobody explains to you
Renting a car in the US is easy. Understanding what "mile marker 142" means, why the next town is 90 minutes away, or what an American 911 dispatcher actually needs from you — nobody hands you that at the rental counter. Here's what's different, and what to know before you're the one stuck on the shoulder.
US highways mostly use mile markers, not kilometre posts
Most of the world marks distance with a kilometre post. American highways instead use a small green sign called a mile marker (or milepost), placed roughly every mile along the shoulder, showing the distance in miles from a point of origin. On Interstates, the numbering usually restarts at the state line — but that pattern isn't universal, and real exceptions exist (Arizona's I-19 is signed in kilometres, not miles). On other roads, the system can vary. Because of that, the number alone isn't quite enough — give the route and the state too.
It isn't decorative. It's how a stranded driver, in a country with genuinely enormous distances between towns, tells someone exactly where they are. More on how mile markers work →
What to say if you call 911
Don't assume the 911 operator can already see your exact location — coverage and system capabilities vary, especially in rural areas. Describe where you are and answer their questions. On a highway, give the state, the route number, your direction of travel, and the nearest mile marker you know:
- The state and route — "Arizona, I-40," "US-93," "State Route 87."
- The direction you're travelling — northbound, southbound, eastbound, westbound.
- The nearest mile marker — the number on the small green sign you last passed. If it's the last one you remember, say so — it may not be your exact current position.
Distances are bigger than they look on a map
A US state can be the size of a small European country. "Just a few inches on the map" can mean two hours with nothing but highway — no town, no fuel station, sometimes no cell signal. Fill up well before the tank looks low, and don't assume the next exit has services just because there is a next exit.
Speed limits and signs work differently
US speed limits are posted in miles per hour, not kilometres per hour — a 70 mph sign is about 113 km/h, easy to misread at a glance if you're used to metric. Distance signs (to the next town, the next exit) are also in miles. Every rental dashboard in the US displays mph by default; if yours has a settings menu, most modern cars let you switch the digital display to km/h even though the posted signs stay in miles — know which one you're reading.
What a state trooper wants when you're pulled over
If a police vehicle with flashing lights comes up behind you, pull over to the right shoulder and stop — don't panic and stop in the lane. Turn off the engine, keep your hands visible on the wheel, and wait for the officer to approach before reaching for anything. Your driving licence, rental agreement, and — if your state and home country require it — an International Driving Permit should all be reachable without digging through the car. It's normal, not alarming — American troopers patrol highways routinely and most stops are for a minor traffic matter.
Laws that change at the state line
The US doesn't have one national traffic code — each state sets its own, and a few catch visitors off guard because they're the opposite of what "most states" do.
- Turning right on red: allowed almost everywhere after a full stop, unless a sign says otherwise. New York City is the reverse — right on red is banned in all five boroughs unless a sign specifically permits it.
- Pumping your own gas: normal everywhere except New Jersey, where self-serve is illegal statewide — an attendant pumps it for you, and they expect you to stay in the car.
- Radar detectors: legal to carry in most states, but illegal in Virginia and Washington, D.C. even switched off in the glovebox. Illegal for commercial drivers everywhere.
- Drink-driving limit: 0.08% blood alcohol almost nationwide — except Utah, at 0.05%, the strictest in the country.
- Cannabis: legal for adults in many states, but it is illegal everywhere to drive under its influence, illegal to carry it across a state line even between two legal states, and illegal on federal land (national parks, military bases) regardless of state law.
- Cell phones: most states now ban holding a phone at all while driving; a handful only ban texting. If your rental doesn't have hands-free built in, assume holding the phone is illegal until you check.
The one number worth saving before you drive
911 is the emergency number nationwide — police, fire, medical, all one number, and it works from any phone including a rental's, even without a US SIM. For a breakdown that isn't an emergency, your rental agreement's own roadside-assistance number comes first — save it before you leave the counter, not after you need it.
Know your mile marker before you need it
The single best thing you can do is not wait until something goes wrong to figure out where you are. The MileCheck app shows your exact route, direction, and nearest mile marker in real time as you drive, across all 50 states — free to use, no account required. If you ever do need to call for help, the answer is already on your screen.
Know exactly where you are — live
Your mile marker is always free to check, even offline. Live DOT alerts and the nearest camera on your route are part of MileCheck Premium and need a connection to update. Runs on CarPlay and Android Auto.
Questions, answered
What is a mile marker on a US highway?
A small green sign posted roughly every mile along the shoulder of a US highway, showing the distance along that road from its starting point or the state line. It's the main way American drivers — and 911 dispatchers — describe an exact location on a long highway.
What should I tell 911 if I don't know exactly where I am in the US?
Don't assume the operator can already see your exact location. Describe where you are and answer their questions — on a highway, give the state, route number, direction of travel, and the nearest mile marker you know. If it's the last one you passed, say so.
Are US speed limits in miles or kilometres?
Miles per hour. A posted "70" means 70 mph, roughly 113 km/h. Distance signs to the next town or exit are also in miles, not kilometres.
Do I need an International Driving Permit to drive in the US?
It depends on your home country and the state you're driving in — some accept a valid foreign licence alone, others expect an International Driving Permit alongside it. Check before you travel, and keep both with your rental agreement where you can reach them quickly.
What do I do if I get pulled over by police in the US?
Pull onto the right shoulder, stop, turn off the engine, and keep your hands visible on the wheel. Wait for the officer to approach before reaching for documents. It's a routine, common occurrence on American highways.
Do US traffic laws vary by state?
Yes — there's no single national code. Most rules are similar, but a few flip entirely: New York City bans right turns on red where most of the country allows them, New Jersey requires an attendant to pump your gas, and Utah's drink-driving limit (0.05%) is stricter than the 0.08% used almost everywhere else.
Can I turn right on red in the US?
Generally yes, after a full stop, unless a sign says otherwise — except in New York City, where it's banned in all five boroughs unless specifically signed to allow it.
What is the move-over law in the US?
Every state has one, but coverage varies. All states protect emergency vehicles at minimum; many extend that to any vehicle with hazard lights on, including a stranded driver. Change lanes away from a stopped vehicle if you can do it safely; if you can't, slow down instead.
Is there an app that shows my exact location on US highways?
Yes — MileCheck shows your current route, direction, and nearest mile marker in real time, in all 50 states, free to use with no account required. It's built for exactly this: knowing precisely where you are on a highway with no other landmarks in sight.