Driving in the United States on a French licence: IDP or not, 4-way stops, school buses and everything that genuinely surprises you on a first road trip

Good news first: for a tourist stay, a French driving licence is accepted in most US states, and thousands of travellers rent a car every year on their national licence alone. But driving rules are set by each state, not by the federal government, and some states — and some rental companies — additionally ask for an International Driving Permit. Our position is simple: get one before you leave, every time. In France the application is free and done online, but processing times can be long, so start several months ahead.

One clarification that avoids a lot of confusion: the International Driving Permit is not a stand-alone licence — it is merely an official multilingual translation of your French licence. It never replaces the original and has no value on its own: at a roadside stop as at the rental desk, you must always present both documents together. Bring your passport when collecting the vehicle too; most rental companies ask for it along with a credit card in the main driver's name.

If you are staying longer than a tourist trip — a job posting, a study semester, a work visa — the rules change, and some states require you to obtain a local licence after a few weeks or months of residency. That scenario goes beyond road-trip territory: check the rules of the relevant state's DMV before you go.

The 4-way stop is the great classic of the American intersection: four stop signs, one on each approach, and a golden rule — first to arrive, first to go. Everyone comes to a complete stop, then vehicles pull away in order of arrival; if two arrive at the same time, priority goes to the vehicle on the right. The system works remarkably well because everyone plays along: make a genuine stop, remember who was there before you, and go when it is your turn without dithering — hesitation is what creates confusion.

The right turn on red surprises in the opposite direction: unless a sign explicitly forbids it, you are allowed to turn right at a red light after a complete stop, yielding to pedestrians and oncoming traffic. Failing to do so when the way is clear will earn you some irritated honking. One major exception to memorise: the rule is reversed in New York City, where turning right on red is prohibited unless a sign specifically allows it.

The school bus rule, finally, is the one you must never get wrong: when a yellow school bus stops with its red lights flashing and its STOP arm extended, all traffic must come to a complete halt — in both directions, including oncoming. The only exception is a road divided by a physical median, where opposing traffic may continue. Fines are heavy and enforcement is unforgiving; when in doubt, stop. Add one interstate peculiarity to the list: passing on the right is common and tolerated there, so check both blind spots before any lane change.

All speed limits are posted in miles per hour: 1 mph is roughly 1.6 km/h, and rental-car speedometers are calibrated in mph, so simply trust the signs. Limits vary from state to state: expect 65 to 80 mph on rural interstates (roughly 105 to 130 km/h), much less in urban areas, and very low-speed school zones at school hours, marked by flashing signs that deserve to be taken seriously.

Speed enforcement relies less on automated cameras than in France and far more on patrols: police cars lurking in the median, mobile radar, even aircraft in some states. Our rule of thumb: stay with the flow of traffic, neither clearly faster nor clearly slower than everyone else, and beware of abrupt limit drops at the entrance to small towns — a classic hunting ground.

If you are pulled over, protocol matters: pull over to the right as soon as it is safe, switch off the engine, stay in the vehicle and keep your hands clearly visible on the wheel. Never get out of the car unless asked, do not reach for your documents in the glovebox before being told to, and announce your movements. The exchange is usually courteous and quick: licence, vehicle papers, possibly a ticket, and everyone moves on.

Fuel is sold by the gallon — about 3.8 litres — and the posted prices look deliciously low until you do the conversion. Virtually all stations are self-service: park alongside the pump, pay, fill up. The standard fuel is called regular (87 octane) and suits almost every rental car; watch out for the green handle, which in the US often denotes diesel — the opposite of the French colour code.

The classic trap for foreign drivers: paying by card directly at the pump very often requires a five-digit US ZIP code, which blocks most foreign cards. The workaround is simple: walk into the store, give your pump number and the amount you want ("40 dollars on pump 3") or leave a card pre-authorisation, then fill up. At some stations you prepay and any unused balance is automatically refunded.

One last habit to build, especially out West: manage your range as a resource. On some stretches of California, Nevada, Utah or Arizona, gas stations can be very far apart, and "next services" signs deserve a careful read. Our rule: never drop below half a tank in sparsely populated areas, and fill up before every long desert crossing.

On age: rental is generally possible from 21, but drivers under 25 are charged a daily young-driver surcharge that can add up painfully over a three-week road trip — factor it into your price comparison from the start. The licence must usually have been held for at least a year, and every additional driver must be named on the contract to be covered.

American insurance jargon baffles French travellers, and it is where the real price differences between offers lie. LDW or CDW (Loss/Collision Damage Waiver) covers damage to the rental vehicle and theft: it is the equivalent of an excess buy-out, often with a zero deductible in the US. SLI (Supplemental Liability Insurance) is additional third-party liability cover, and it is crucial: the liability limits legally included in American rentals are very low compared with the real cost of an injury accident in the United States. Check what your package already includes (rentals prepaid from France often bundle LDW and SLI) before accepting anything sold at the counter.

Speaking of the counter, expect an insistent walkthrough of the options: upgrade, prepaid fuel, roadside assistance, toll transponder. Nothing sinister — it is the business model; politely decline whatever duplicates your package, and take the time to photograph the vehicle from every angle before leaving the lot, wheels and windscreen included.

The number-one mistake of a first American road trip has nothing to do with traffic law: it is underestimating the distances. On the map, chaining Las Vegas, the Grand Canyon, Monument Valley and Page looks reasonable; behind the wheel, it means entire days on the road, at real average speeds far below what the ideal itinerary suggests — photo stops, roadworks, 35 mph park roads and unplanned detours included. Our planning rule: sensible legs, rarely more than three to four hours of actual driving per day, and an extra night in the same place whenever the itinerary allows.

Fatigue is the other side of the problem, made worse at the start of the trip by jet lag, which cuts into sleep and shifts your alertness. This is not just guidebook caution: a study by Jane Stutts and her co-authors published in Accident Analysis & Prevention shows that prolonged driving, night driving and sleep debt are among the main risk factors for sleep-related crashes (available via Google Scholar: scholar.google.com/scholar?q=Stutts+driver+risk+factors+sleep-related+crashes). In practice: no long leg on arrival day, no night driving in wildlife country, and a proper break every two hours.

Managed well, this slower rhythm is precisely what makes an American road trip special: the back roads, the diners in the middle of nowhere, the viewpoints you stop at without having planned to. Our pages on the Grand Canyon and California's Highway 1 give examples of realistic legs, and our United States guide gathers all our road-tested itineraries.