Every country boils down to one-third landscape and two-thirds people. Let a traveller cover a nation from coast to coast. Let him visit every monument and admire all its natural beauties. Let him live off the fat of its land, take a million photos and send home ecstatic postcards. Unless the traveller meets locals, and learns to know them on their own turf, he will remain two-thirds short of even the foggiest notion of where on earth he has been. For any free spirit possessed of real curiosity and a degree of fortitude travelling by good old proletarian bus is an unceasing revelation: a way not just to see the country - a way to befriend it. And nowhere is this wonderful intimacy more likely to occur than in the United States of America, where the general populace is innocent of shyness or awe and the average length of a bus journey easily accommodates uninhibited confidences.

During happy months spent criss-crossing America on Greyhound Buses I met students and strippers, gamblers on their uppers, Quakers, Amish and similarly thrifty sectarians, and scores of ordinary Americans who for one reason or another - decrepitude or youth, poverty, criminality, illness or genuine concern for the planet - do not use a car. As the magnificent countryside unrolled outside the windows, loquacious strangers exchanged opinions and personal history. Occasionally overcome by a longing for silence and solitude, I learned that if I faked a hacking cough or - explain it if you can! - was seen to be writing in a notebook, new boarders gave me a wide berth. American buses are democratically filled, first-come, first- serve, and it is worth arriving early at the terminal to secure a window-seat. Sometimes, when there was no pregnant or disabled passenger with priority, I was bold enough to snare the front seat. The views through the windscreen of a Greyhound Bus - dawn waking the flatlands of Kansas, great cities gathering themselves slowly out of America' s rural heartland - are the most engulfing and dramatic on the open road. However, because of the front seat's proximity to the driver, whose authority on a long-haul bus is as absolute as a captain's at sea, its occupant is subtly raised and separated from his fellows. The position therefore tends to attract exhibitionists and snobs doing their best to show they wouldn't be there, except for the fact that their cars are in for servicing.

And the smug blonde in the front seat turned to smirk and nod at us lesser types.

Nice ordinary Americans choose the middle rows; by tacit agreement preferring to sit next to their own sex and race. Yea verily, as, since the first bus was launched, bad boys go straight to the back.

Often I chose my next stop - Dinosaur, Bald Knob, Sault Sainte Marie - simply because I liked the sound of it. My book of blank tickets, bought in advance from Greyhound's English agent, did not hold me to any itinerary. But 99 out of 100 of my fellow passengers were purposefully en route, some to visit family, others to job hunt, and a few to flee trouble or find a new place to make trouble, never to start it on the bus. Though we were boarded in South Texas by armed police searching for 'illegals', and by Louisiana troopers looking (fruitlessly) for a fugitive wife who had fatally ventilated her husband with a carving knife, there was no violence on board. On the contrary, whatever the boys in the back get up to - drinking bourbon camouflaged in Coke tins and cutting some quiet deals - the Greyhound Bus must be one of the safest places in the USA. Terminals, however, though heavily policed, define the wrong side of the tracks in any town, and the surrounding areas can be threatening. Fortunately, there are taxi ranks outside every station; not once was I steered wrong by a taxi driver when I asked about a clean, cheap place to stay.

The long-distance bus traveller will probably spend at least one night out of every two or three on board. Sleeping on board entails a weird descent through skin after skin of consciousness until the constant Greyhound rock and rumble finally delivers you, its passenger, into dreams. Except on Thanksgiving and holiday weekends, when all Americans go home, the neighbouring seat is likely to be free at night, and with the help of an invaluable inflatable pillow, it could be worse. Sometimes I'd wake momentarily to see the passing ghost of a small town; once I opened my eyes on a flotilla of fairyland lights that turned out to be an oil refinery outside Corpus Christi.

Eating, like boozing and smoking, is forbidden on American buses. Frequent rest stops allow passengers to avail themselves of a more commodious lavatory than the one on board, which is used only in emergencies. ("What do you do about the loo?" is the question most frequently put to old bus hands by bus virgins). While smokers light up, the others rush to satisfy an apparently national addiction to junk food. Too many of the stops are anonymous greasy-spoon burger chains. Once in a while, however, especially in the wild reaches of northern America, where the breadth of a smaller nation lies between cities, the regular stop is somewhere the driver is greeted by name and his 'usual' is already in the oven. For half an hour or so, passengers join authentic Americana in mom-and-pop places like, say, Del's Café. In the backroom of Del's, a bunch of local women setting up a jumble sale had stopped to try on hats and were howling with laughter.

America is a road country, and in the modern era of one-man-one-car, the road uniting all its states can be a lonely, congested, irascible, scary place to be. But not on a big bus. On a Greyhound out of Fargo, I listened as two men behind me swapped recipes for venison sausage. A woman across the aisle had just told us a story about the ghost of a bear said to haunt a forest on Minnesota's Upper Peninsula. My neighbour, an 80-year-old local, bound for her son's home a few hundred miles down the road, began describing the old days, when all her neighbours were homesick immigrants from Russia who thought they had found a replica of the Steppes in the North Dakota landscape.

From the close, safe warmth of the bus, I smiled out at the endless telephone poles etching a dusky sky: my neighbour called them "our local tree". Taking the bus is more than travelling in space: it is nearly travelling in time, too. Taking the Greyhound Bus is as close as any westerly romantic can ever again come to crossing America by stagecoach.