Idaho: the “Potato State” deserves a better nickname. It should also have far more British visitors, for its spectacular landscapes and friendly, diverse people. They include, in the state capital Boise, a large Basque-American population descended from shepherds from northern Spain and southwest France.

With just two million people in a state almost exactly the size of Britain, direct flights to Boise are not viable. But there are plenty of connecting possibilities. And that is the concern of Belinda Stebbings. She contacted me after I wrote about the basics of international connections (specifically in Dubai) because she has a slightly different issue.

“I am trying to book flights to and from Idaho to see my daughter,” Belinda writes. “The nearest airport is Boise. I understand that there is no direct flight. That’s fine in theory but I’m struggling with the connection gap in the US. The time between flights seems to be too short for me as an international traveller to get through passports and customs. My worry is that I might miss my onward connection.

“If I do, what happens – will I have to buy another ticket if I’m stuck in customs?”

Thank you, Belinda, for the chance to explain how this works. A quick online search for May reveals dozens of possible routings from London to Boise, including via Seattle, Los Angeles and Phoenix. But for the swiftest journey time – and a reasonable border experience – I recommend Delta Air Lines from Heathrow via Salt Lake City. The “SLC” hub airport in Utah is small and easy to navigate.

Passengers arriving in the US on flights from overseas flights with onward connections must clear US Customs and Border Protection at their first point of entry. (Incidentally, this also applies to international departures – unlike when you change planes at a Gulf hub, or Istanbul, Singapore, Hong Kong or almost anywhere else.)

The connection from Delta’s inbound flight from Heathrow gives 90 minutes to transfer, including going through passport control, picking up your bag (unless, wisely, you are cabin-baggage-only), clearing customs, dropping the bag and finding your departure gate. Ninety minutes should be more than enough, assuming the departure from London is on time.

Last time I arrived at SLC my flight was 20 minutes late, due to a wait for de-icing at Heathrow, and I had only 40 minutes left before my onward connection to Long Beach, California. There was no stress and no rush. Had it been any later, I would have asked the cabin crew if I could be moved further forward on the aircraft for speedier disembarkation – usually, they are happy to do this to help people make connections. Everyone is on your side.

Sometimes, though, connections go wrong. But as long as you book a through ticket (London-Salt Lake City-Boise), any disruption is the airline’s problem, not yours. Under UK air passengers’ rights rules, which extend to connecting flights, Delta must get you to your destination as close to the scheduled arrival time as possible.

If a delay on the outbound flight is known about in advance, airline staff at Heathrow may proactively book you a fresh itinerary going out via Minneapolis-St Paul. But if the plane gets late once you are on board to Salt Lake City, there is a later SLC-Boise flight that will probably have a few seats empty and you will be automatically rebooked in one.

Three important points to finish:

Statistically, though, the very strong odds are that your flights will be just fine.