I'LL TELL you this, but you'll have to promise that it will go no further. Not long after we moved here we had the people next door round for dinner and - I swear this is true - they drove.

I was astounded (I recall asking them jokingly if they used a light aircraft to get to the supermarket, which simply drew blank looks and the mental scratching of my name from all future invitation lists), but I have since come to realise that there was nothing especially odd in their driving less than a couple of hundred feet to visit us. Nobody walks anywhere in America nowadays.

A researcher at the University of California at Berkeley recently made a study of the nation's walking habits and concluded that 85 per cent of people in the United States are "essentially" sedentary; 35 per cent of the population are "totally" sedentary. The average American walks less than 75 miles a year - about 1.4 miles a week, barely 350 yards a day. I'm no stranger to sloth myself, but that's appallingly little.

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One of the things we wanted when we moved to America was to live in a town within walking distance of shops. Hanover, where we settled, is a small, typical New England college town, pleasant, sedate and compact. It has a broad green, an old-fashioned main street, nice college buildings with big lawns, and leafy residential streets. It is, in short, an agreeable, easy place to stroll. Nearly everyone in town is within a level five-minute walk of the shops, and yet as far as I can tell virtually no one walks.

I walk to town nearly every day when I am at home. I go to the post office or library or the local bookshop, and sometimes, if I am feeling particularly debonair, I stop at Rosey Jekes Cafi for a cappuccino. All this is a big part of my life and I wouldn't dream of doing it other than on foot. People have got used to this curious and eccentric behaviour now, but several times in the early days, passing neighbours would slow beside the kerb and ask if I wanted a lift.

"But I'm going your way," they would insist when I politely declined. "Really, it's no bother." "Honestly, I enjoy walking." Well, if you're absolutely sure", they would say, and depart reluctantly, as if they felt they were leaving the scene of an accident.

People have become so habituated to using the car for everything that it would never occur to them to unfurl their legs and see what they can do. Sometimes it's almost ludicrous. The other day I was in a little nearby town called Etna waiting to bring home one of my children from a piano lesson when a car stopped outside the local post office and a man about my age popped out and dashed inside (and left the motor running - something else that exercises me inordinately). He was inside for about three or four minutes, then came out, got in the car and drove exactly 16 feet to the general store next door, and popped in, engine still running.

And the thing is, this man looked really fit. I'm sure he jogs extravagant distances and plays squash and does all kinds of exuberantly healthful things, but I am just as sure that he drives to each of these undertakings. It's crazy. An acquaintance of ours was complaining the other day about the difficulty of finding a place to park outside the local gymnasium. She goes there several times a week to walk on a treadmill. The gymnasium is, at most, a six-minute walk from her front door. I asked why she didn't walk to the gym and do six minutes less on the treadmill.

She looked at me as if I were tragically simple-minded and said, "But I have a programme for the treadmill. It records my distance and speed, and I can adjust it for degree of difficulty." It had not occurred to me how thoughtlessly deficient nature is in this regard.

According to a concerned and faintly horrified recent editorial in the Boston Globe, the United States spends less than 1 per cent of its $25bn- a-year roads budget on facilities for pedestrians. Actually, I'm surprised it's that much. Go to almost any suburb developed in the last 30 years - and there are thousands to choose from - and you will not find a pavement anywhere. Often you won't find a single pedestrian crossing. I am not exaggerating.

I had this brought home to me last summer when we were driving across Maine and stopped for coffee in one of those endless zones of shopping malls, motels, petrol stations and fast-food places that sprout everywhere in America these days. I noticed there was a bookshop across the street, so I decided to skip coffee and pop over. I needed a particular book and anyway I figured that this would give my wife a chance to spend some important private quality time with four restive, overheated children.

Although the bookshop was no more than 50ft or 60ft away, I discovered that there was no way to get there on foot. There was a traffic crossing for cars, but no provision for pedestrians and no way to cross without dodging through three lanes of swiftly turning traffic. I had to get in the car and drive across. At the time it seemed ridiculous and exasperating, but afterwards I realised that I was probably the only person ever even to have entertained the notion of negotiating that intersection on foot.

The fact is, Americans not only don't walk anywhere, they won't walk anywhere, and woe to anyone who tries to make them, as a town here in New Hampshire called Laconia discovered to its cost. A few years ago Laconia spent $5m on pedestrianising its town centre, to make it a pleasant shopping environment. Aesthetically it was a triumph - urban planners came from all over to coo and take photos - but commercially it was a disaster. Forced to walk one whole block from a car park, shoppers abandoned downtown Laconia for suburban malls.

In 1994 Laconia dug up its pretty brick paving, took away the benches and tubs of geraniums and decorative trees, and put the street back to the way it had been in the first place. Now people can park right in front of the shops again and downtown Laconia thrives anew. And if that isn't sad, I don't know what is.

`Notes from a Big Country' by Bill Bryson is published by Doubleday, price pounds 16.99