Red tape, cancelled flights and yet more red tape. Simon Calder, Travel Editor, points out how crossing the pond can lead to that sinking feeling

Anyone who happens to cycle around some of the more fashionable quarters of London early in the morning will be familiar with knots of forlorn people shivering outside imposing buildings. They are seeking permission to travel.

Anyone who happens to cycle around some of the more fashionable quarters of London early in the morning will be familiar with knots of forlorn people shivering outside imposing buildings. They are seeking permission to travel.

The straggle along the Bayswater Road pertains to the Russian Consulate; getting a visa to travel to St Petersburg is tougher than it was at the height of the Cold War, when the consulate was Soviet and the destination was known as Leningrad. On the far side of Hyde Park, those with the misfortune to have been born outside Europe are queuing up outside the French Consulate: a Quebecois residing in London must apply for permission even to nip over to Paris on the Eurostar. But neither experience is so stressful and undignified as the line waiting to enter the US Embassy in Grosvenor Square.

Understandably, given the attacks on American interests abroad, security is heavy. You cannot lock up your bike within the Square without a couple of armed police asking you to move it. A gap in the makeshift barricade is guarded by an official who will scrutinise your credentials to decide if you can be allowed to approach the door. The personal searches on the way into the embassy are, naturally, intrusive.

Even to get this far you have had to spend a small fortune: the price of making a visa application is £65, plus a few quid on the premium-rate phone number to make an appointment for an interrogation - sorry, interview - with an immigration official.

At the end of this process, there is no guarantee that you will be granted a visa. If you are successful, it amounts to nothing more than permission to apply for admission to the Land of the Free, and to be photographed and fingerprinted upon arrival. This procedure applies whether you are planning a six-month trip of a lifetime across America, or are merely changing planes at Miami airport en route to the Caribbean.

Fortunately, the majority of British travellers to America this year will not have to undergo such an ordeal. Most of us can enter the country under the Visa Waiver Program. But anyone who has ever been arrested for any offence, anywhere in the world, must apply for a visa at the US Embassy in London or the American Consulate in Belfast. This applies even if the arrest did not result in any criminal proceedings, or if a conviction is regarded as spent under British law. The same goes for anyone whose passport is issued after 26 October this year, unless it includes encrypted biometric information - a digital record of unique physiological or behavioural characteristics - which is still several years down the technological line.

Having acquired permission to visit America, your problems are only just beginning. You may be blissfully unaware of the rights of US government agencies to check out your credentials in the airline's reservations computers. Officials from two dozen agencies may dig around to find out, among other information, the people with whom you are travelling, your meal preferences and how you paid for your ticket.

With luck, this information will not raise sufficient fears to trigger the cancellation of the transatlantic flight. But don't bet on it. So far this year, British Airways has been ordered to ground flight 223 from Heathrow to Washington four times. BA has warned that forward-bookings have been affected by the continuing uncertainty - and America's beleaguered tourist industry can hardly believe its misfortune. This year should be the best yet for visitor numbers to the US. By rights, millions of travellers should be taking advantage of the weak dollar to enjoy the wide-screen experience only America can offer.

British travellers comprise the one major market not to show a decline in visits to America last year. We may be divided by a common language, but we have loved the place and its people since 1977, when Sir Freddie Laker launched cheap flights to New York . This year, though, I suspect many of us will take advantage of the dwindling dollar to visit countries whose currencies are either formally or structurally tied to the dollar. Tourism bosses in the Caribbean, Latin America and Asia should raise a colourful cocktail to Tom Ridge, the Secretary for Homeland Security, for the deterrents against overseas visitors.

Every rational traveller will sympathise with Americans' feelings of vulnerability following 11 September, 2001, and understand the national desire to make frontiers as safe as possible. Yet the ever-stricter rules and structures imposed by the US Department of Homeland Security make a transatlantic trip appear more daunting than an A-level in physics followed by a trip to the dentist. That's not what I call a holiday.