How to plan a US road trip

The contiguous United States spans four time zones, and driving from coast to coast without stopping to look at anything takes the better part of a week. Within a single western state, the distance between two headline attractions can exceed the length of an entire European country.

Convert everything to hours before you commit. A day with six hours of driving leaves time for one significant stop, not three, and the difference between a five-hour and an eight-hour day is the difference between a holiday and a haulage job.

Interstates are fast, dull and reliable. US routes and state highways are slower, more interesting and pass through towns. Designated scenic byways are slower still and are usually the reason to be there at all. A good route mixes them deliberately rather than accepting whatever the navigation app calls fastest.

Note that not every state observes daylight saving time, and a route crossing several time zones will move your effective arrival time in ways that matter when the last check-in is at nine in the evening.

Distances between services vary enormously. In the eastern half of the country you are rarely far from fuel, food and a bed. Across parts of the interior west, the gap between towns with reliable fuel can be a hundred miles or more, and the last station before a long empty stretch is a fixed point on your plan.

Terrain changes the arithmetic. Mountain passes, canyon roads and unpaved forest routes take far longer than the mileage suggests, and some are unsuitable for a low rental car or a large motorhome — restrictions that appear on park websites rather than in navigation apps.

Finally, build in one buffer day per week. Weather closures, a mechanical problem, a place worth an extra night, or simple fatigue will consume it, and an itinerary with no slack turns every minor disruption into a cascade of cancelled bookings.

List the fixed points first — the two or three places that are the actual reason for the trip. Everything else is connective tissue and can move; these cannot, because their availability is the binding constraint.

Check what those places require to enter. Several popular national parks operate timed entry or vehicle reservation systems during peak months, and some famous trails and permits are allocated by lottery months ahead. The park's own website is where these are announced and where the rules change year to year.

Book the constrained inventory as soon as its window opens. Federal campsites, cabins, tours and many permits are released through the central federal recreation booking system on rolling windows, and popular sites are gone within minutes of release. Park lodges run their own systems and open even earlier.

Now build the driving around those dates, converting each leg into hours and checking the arrival time rather than the distance. Aim to arrive before dark, particularly anywhere rural, and put the longest drives on days without a timed entry to make.

Reserve the flexible accommodation next, at a level of commitment matching how confident you are. Refundable rates on interstate motels cost slightly more and buy the ability to change the plan when the weather does.

Check seasonal access for every mountain or high-altitude section. Roads across high passes commonly open in late spring and close in autumn, sometimes without a fixed date, and a route that works in August does not exist in May.

Read the park alerts pages and the weather forecast for each leg in the days before you travel. Wildfire smoke, flash flooding in canyon country, winter storms in the mountains and hurricane season on the southeastern coast all close roads at short notice.

Download offline maps for the whole route, and take a paper road atlas for the western half of the country. Both cost almost nothing and both work when there is no signal, which is a large fraction of the interesting driving.

Fuel is the easiest cost to estimate precisely. The federal fuel economy site publishes a trip calculator that combines your route with the rated consumption of a specific vehicle, and the Energy Information Administration publishes current average prices by region, which vary substantially between states because of differing taxes.

Accommodation dominates most budgets. Interstate motels are cheap and consistent, national park lodges are expensive and booked out, and campsites are cheapest of all if you are equipped for them. Prices swing hard with season, and a room near a park entrance in July bears no relation to the same room in October.

Federal entrance fees are charged per vehicle at most parks and are valid for several days. If you plan to visit several federal sites, the annual pass covering national parks and other federal recreation areas usually pays for itself within a few visits, and free entrance days are published each year.

Tolls are increasingly cashless. Many bridges, tunnels and turnpikes photograph the plate and bill the registered owner, which for a rental means the rental company pays and adds an administration fee per toll or per day. Ask about the transponder policy at pick-up, because the fees can exceed the tolls.

City parking is a real line item and a frequent surprise: overnight hotel parking in major cities can cost as much as a night in a rural motel, and street parking rules are enforced aggressively. Check before booking accommodation in a city centre.

Food costs are controllable and the place most road trips leak money. A cool box, a supermarket stop and picnic lunches at scenic pull-offs are cheaper and better than three restaurant meals a day. Remember that the menu price excludes tax and tipping is expected on table service.

If you are budgeting from scratch, the federal per diem rates used for government travel are a useful yardstick for what lodging and meals should cost in a given county — they are published by location and reflect real local prices.

For electric vehicles, plan charging as an itinerary constraint rather than a cost question. Charging networks are dense along major corridors and thin across the interior west, and a route that assumes urban charging density will strand you.

Service the car before a long trip: tyres including pressure and tread and the spare, brakes, fluids, wipers, lights, and the battery if it is more than a few years old. Breakdowns cluster in exactly the remote places where recovery is slowest and most expensive.

Confirm roadside assistance cover before departure, whether through your insurer, a motoring club or the vehicle manufacturer, and know the number. In remote areas a tow can be a hundred miles, which is a serious bill without cover.

For a rental, work out the insurance position deliberately rather than at the counter. Your own auto policy may extend to rentals, some credit cards provide collision damage cover as a benefit when the rental is paid on that card, and visitors from abroad usually have neither. Check what liability cover, as distinct from damage cover, you actually hold.

Rental terms deserve a read: additional driver fees, under-25 surcharges, one-way drop charges that can exceed the rental itself, mileage limits on some deals, restrictions on unpaved roads, and the fuel policy. Photograph the vehicle at pick-up and drop-off.

If you are driving to a trailhead or a remote area, carry water beyond what you expect to need, food, a torch, a first aid kit, jumper cables, a tyre inflator or repair kit, and warm layers regardless of season. Desert days and mountain nights differ by more than visitors expect.

Fit a phone mount and set navigation before moving. Handling a phone while driving is illegal in a large and growing number of states, and enforcement is routine.

Keep documents accessible: driving licence, rental agreement, insurance evidence and vehicle registration. If you are a visitor, carry your passport and immigration documents in the car rather than in checked luggage at the hotel.

For anyone driving their own car far from home, check that the registration and inspection will not expire mid-trip, and carry the insurance card. Roadside checks are routine at some state lines and border checkpoints in the southwest.

Traffic drives on the right, and most rental cars are automatic. The unfamiliar parts are not the lane discipline but the intersections: four-way stops where the first to arrive goes first, and a permitted right turn on a red light after stopping unless a sign forbids it.

School buses stop traffic in both directions when their lights flash and the stop arm extends, except on divided highways in some states. This rule is enforced severely and is the one visitors most often break without realising.

Speed limits are set by state and change at state lines, and are enforced by state and local police using both radar and aircraft in some places. Move-over laws requiring you to change lane or slow for stopped emergency and service vehicles now exist in every state.

Seat belts are compulsory, and child restraint requirements are strict, specific and vary by state — for a family trip crossing several states, check the strictest rule on your route and use that.

Visitors can generally drive on a foreign licence for a limited period, sometimes with an international driving permit, and rental companies may require one depending on the licence language. The rules are set by each state, so check the states you will actually drive in.

If you are stopped by police, pull over promptly to the right, stay in the vehicle with the window down and hands visible on the wheel, and tell the officer before reaching for documents. This is normal practice in the United States and misunderstanding it causes avoidable tension.

Rural driving has hazards city drivers underestimate: wildlife at dawn and dusk, unlit roads, gravel shoulders, long uphill grades where slow trucks appear suddenly, dust storms in the southwest and black ice in the mountains. Reduce speed at dusk and increase following distance.

Fatigue is the underrated risk on a long trip. Long straight roads and cruise control are hypnotic, and the safety data on drowsy driving is consistent with what every driver already suspects. Stop every couple of hours, and stop entirely when you notice the drifting.

The national parks are only part of the picture. National forests, Bureau of Land Management land, national monuments, wildlife refuges and state parks all offer comparable scenery with fewer people and simpler access, and they cover an enormous share of the western landscape.

Federal campsites are booked centrally, months ahead for the popular ones, and each campground publishes its own rules on vehicle length, hook-ups, generators and food storage. First-come first-served campgrounds still exist and are how flexible travellers get into full parks.

Dispersed camping on public land is permitted in many national forest and Bureau of Land Management areas, generally free and without facilities, subject to local rules on fire, duration and distance from water. Check the specific district's rules rather than assuming.

Wildlife rules are safety rules. Keep the distances parks specify, never feed anything, and use the food storage lockers where bears are present — food left in a car is a broken window at best. In the desert, the relevant hazards are heat and water rather than animals.

Altitude affects visitors more than they expect. Several major western parks sit high enough to cause headaches and breathlessness on the first day, so plan an easy first day at elevation and drink more water than feels necessary.

Check accessibility and pet rules before arriving. Most national parks restrict dogs to developed areas and prohibit them on trails, which is a trip-defining constraint for anyone travelling with one.

Finally, treat ranger stations and visitor centres as the best information source available. They know which roads are open, which trails are flooded, where the smoke is, and what is worth doing that day — and none of that is on the internet at the resolution they hold it.