Geert Mak: In America - Travels With John Steinbeck.

£25. Harvill Secker.

In 1960, John Steinbeck feared for his health, his talent and his country. Muttering against the dying of the light, the novelist bought himself a truck he called Rocinante and installed his dog, Charley, in the passenger seat. They set off to traverse the continent. The result was one of America's best-loved books.

There are problems, though, in Travels With Charley. Steinbeck's difficult son, John Jnr, was blunt enough. Speaking on behalf of himself and his brother, he stated that "Thom and I are convinced that he never talked to any of those people... He just sat in his camper and wrote all that sh*t". In recent years, several scholars and journalists have come to the same conclusion. Geert Mak, in his understated way, cannot avoid a banal reality.

So: those lovely scenes of Steinbeck preparing to bed down under the vast bowl of a western sky? It seems he was in a local motel. That idyllic day spent fishing with a young man he just happened upon? Judging by times, dates and distances travelled, the chances were close to impossible. Discovering the real America? In Mak's telling, the novelist couldn't wait to get the hell out of whichever emblematic little burg he encountered.

This provides some problems, in turn, for the Dutch writer. He offers a companion volume to his marvellous In Europe, but his sub-title is close to misrepresentation. These are not "Travels With John Steinbeck". For page after page - for dozens of pages - the novelist disappears from the narrative. Often, he had little to say. As often as not, what he had to say cannot be trusted. The attempt at a composite portrait of America now and the US half a century ago runs aground on the shoals of sheer fiction.

Mak is left to shift for himself. This is no bad thing. He no more needs the fabricated experiences of the man who wrote Cannery Row than Steinbeck needed the inspiration - on his wife's advice - of R.L. Stevenson's Travels With a Donkey. Another metaphor lives within In America. It has to do with something that troubled John Steinbeck in 1960 and disfigured his own Travels. Faced with an endlessly re-invented country, people make stuff up.

Mak is a European. The fact comes up repeatedly as he gazes in wonder at a democracy consumed by self-regard, supreme in its complacency, and utterly callous towards its weakest members. Why do Americans believe that their country is the greatest thing the world has seen when their roads are crumbling and their bridges falling down? What becomes of exceptionalism when it depends on hideous corruption and naked power? More important: why do the citizens of the republic refuse to doubt the old dream?

As Mak shows, time and again, the average American is no longer proud, prosperous, or confident. The dream they speak of ended long ago. The farmers are cleared from the land, the fishermen from the sea. The ranchers in the big hats and boots are an endangered species. Detroit is a post-historical wasteland and the automotive industry turns out second-rate heaps that could barely compete against a Trabant. But America believes.

Mak, who seems to have first encountered the republic as a young man drunk on rum not many years after Steinbeck abandoned his road trip, is acute on the subject of delusions. He believes, on the one hand, that if the US persists with its fantasies the rest of us will have no end of trouble. Pitiless wars, on that reading, are clues. Equally, the author thinks that awakening from the American dream, the old vision scented by Tocqueville and Twain, won't help humanity.

Perhaps the most striking thing about In America is the absence of glamour. The US, in Mak's depiction, is an impoverished, near-squalid place whose natural wonders do not quite compensate for the fact that times are hard, folks are afraid, and there is no Franklin Roosevelt to vanquish "fear itself". Common folk are living on the edge, from Maine to California, and still telling themselves that to be American is to be blessed.

Steinbeck sensed it: Mak allows that much credit. In 1960, the writer about to receive his Nobel - self-conscious and shame-faced - detected a fakery in his country that he ascribed to moral failures. Such language is no longer in use: the fact itself might count as revealing. But the writer who put great words into the mouth of Tom Joad could not find many useful things to say about motels with plastic-wrapped cutlery.

It was as though those facts spoke for themselves. Steinbeck's best joke was to allow Charley, one of the big Poodles, to relieve himself all over that America. But the writer also grieved. Worse, he could no longer find words for grief. He was just 58 when he drove hell for leather across his country, consuming more speed than Kerouac ever imagined, and found no relief. That glimpsed story is sad.

The novelist gave up, in the end, before he made it back to Sag Harbor, just upwards of Long Island, where he was liked by his political enemies and endured, it seems, by his pals. Mak packs it in too before he has traced a circle around America, as though his book's conceit has been less reliable than his Jeep. On both counts, that stands as a shame. Stevenson and Twain, with far fewer motels, roughed it across the plains with a lot less fuss, and better prose.

For all that, Mak has written a book that might yet turn out to be important. In these early years of a new century, America has become a puzzle to which all should attend. Good folks in Illinois and Vermont still have the voting power to blow the rest of us back into the Stone Age. Nice people in Montana - on whom Mak is excellent - still think that God gave them charge of the planet. A writer raised on Dutch Presbyterian religiosity handles the psychology well. America believes, still, in the importance of America.

Half a century back, Steinbeck was desolate and lost. He encountered no Joads. Out on the highway, in the dark, with snow and rain coming down, he caught no echo of his own words. As the son said, it was just "all that sh*t", invented for a purpose by a man who needed and wanted to believe. For most of us, it would do, but it ended John Steinbeck's writing life.

That, though, would be another story. Mak's book alludes continually to the tales he might have told. In the end, somehow, he depends on those. You part from him and his wife, as you do from Steinbeck and Charley, still wondering about all the invented stories on the lost highways of America. Then you wonder why anyone needs American stories so very badly.

The magic of America, heard by Tocqueville and Stevenson alike, is this: a tall tale, well told, will charm all. Washington Irving reckoned that a century could fly past, quick as another motel sign, before you woke. Just as long as you minded the difference between a truth and a falsehood. And who was telling the story.