When Gary Younge arrived in America as the Guardian's New York correspondent, he found a nation simultaneously united in its myopic nationalism and at bitter war with itself. But what surprised him was how, for all its differences, it wasn't too dissimilar to Blair's Britain, as he reveals in this extract from his new book

When I arrived in New York from London in January 2003 to take up my post as the Guardian's New York correspondent, the United States appeared to be in the grip of a monumental emotional spasm. The terrorist attacks of September 11 2001 seemed to have left it incapable of empathy with the outside world.

The previous year, global opposition to the impending war in Iraq had grown alongside a tacit understanding that it would probably happen anyway. In the US, people were intellectually preparing themselves. The top five non-fiction titles on the New York Times bestsellers list for that first month were: 1) Bush at War; 2) The Right Man (Bush's former speechwriter relives his first year in the White House); 3) Portrait of a Killer (Patricia Cornwell on Jack the Ripper); 4) The Savage Nation (A rightwing radio talk-show host saves America from "the liberal assault on our borders, language and culture"); and 5) Leadership, by former Republican New York mayor Rudolph Giuliani.

Britain stood virtually alone among its western Europe neighbours in its desire to anticipate and replicate the Bush administration's every move. Reporting from the United Nations during my first few months felt like living in a parallel universe where mind and muscle operated completely independently. While most diplomats were trying to avert the war, the US and British armies were amassing huge numbers of troops in the Gulf and steeling themselves for battle.

It was into this cauldron of destiny, demagoguery and despair that I sought to translate, explain and explore the United States for a British audience. As a child of empire - my parents left Barbados in the early 60s for England, where I was born - I was ambivalent about both the growing tides of Euro-bashing and anti-Americanism on either side of the pond.

I came less in the tradition of Alexis de Tocqueville than that other great chronicler of American civilisation, the Trinidadian socialist CLR James. Not so much transatlantic as Black Atlantic. Coming from a nation that had interned the Irish and massacred the Mau Mau, the only thing I found exceptional about Abu Ghraib was that the perpetrators there had been caught on camera.

"A person is smart," says Tommy Lee Jones in the film Men In Black, when asked why he hides the existence of aliens on Earth from ordinary people. "People are dumb, panicky, dangerous animals and you know it." There was no reason to believe that the American people would be any different in that regard to western Europeans when they had their privilege challenged and their lives threatened.

Time and again, while on the road, I would experience just how warm, wonderful and occasionally warped Americans can be. In Montgomery, Alabama, the cradle of the Confederacy, I was driven the wrong way up a one-way street by a young white woman high on life and Martini whom I had only just met. By day, I was covering Rosa Parks' memorial services. By night, I accompanied my new companion from gay bar to night club, drinking plenty and talking about drugs as though the cast of Letter to Brezhnev had ended up in the Deep South.

In Salt Lake City, the main town in the most conservative state in the union, I would wait for the mayor in a Hispanic biker bar, watching slides beamed onto the wall of scantily clad women writhing around on motorcycles. In Mississippi, three elderly people threatened to shoot me when I asked directions. A few months later, in the same state, a policeman would threaten to jail me for "giving him a look".

I have always found America exciting; but, for better or worse, never exceptional. Its efforts at global domination seemed like a plot development in the narrative of European empire rather than a break from it. Even as the French lambasted secretary of state Colin Powell's presentation to the Security Council, protesters in Abidjan, the capital of Ivory Coast, waved American flags and placards saying: "Bush please help Ivory Coast against French terrorism." There was precious little moral high ground to go round. Yet everyone, it seemed, was making a stake on it.

So it was with great bemusement that I found myself having to absorb abuse from white, rightwing Americans, who harked back to the Declaration of Independence of 1776 and the second world war to justify military aggression in Iraq. They badgered me as though their own reference points represented the sole prism through which global events could possibly be understood. As if the struggle for moral superiority between Europe and the US could have any relevance to someone whose ancestors were brought to the Americas as slaves and whose parents and grandparents lived through the war under European colonisation.

"If it wasn't for us, you would be speaking German," they would say. "No, if it wasn't for you," I would tell them, "I would probably be speaking Yoruba."

However, the sanctimony with which many liberal Europeans criticised the Bush administration was no less galling or historically illiterate. Their critique of US foreign policy was often sound, but the haughtiness with which they delivered it was way off key. When their governments or citizens slam America for its brutality and imperialist pretensions, all too often they fail to do so with sufficient self-awareness or humility to see what, to the rest of the world, is obvious: that their nations have acted in an equally pernicious fashion whenever they have had the opportunity.

As for me, I came not with an agenda but with a view: that while America's imperial intentions represented a sequel to European colonialism, that did not make those ambitions any more morally defensible or the world any less precarious. While Europeans had no grounds to be pious, the whole world had every reason to be concerned. September 11 had revealed the potential destructiveness of religious fundamentalism. The Bush administration's subsequent actions indicated that nationalist and economic fundamentalism could wreak at least as much havoc and harm.

Not long after I arrived in America, I realised that one political misconception, above all, had dominated. While I was well aware that there were many Americans who were opposed to the Bush agenda (my wife being one of them), I had no idea that their number amounted to a significant critical mass. This was not a ludicrous misreading of the situation. I arrived just a few months after the Republicans had cemented their control of both House and Senate. Bush's approval ratings were high and opposition to the war was soft compared with every other country in the world apart from Israel.

But as the war faltered and the economy stalled, opposition mounted. The growth and crystallisation of this opposition took place for the most part under the radar. The mainstream news media either underreported it, misreported it or derided it until the moment when it became impossible to ignore. But it was always there.

America was, in short, bitterly divided. By the end of my first year, a Time/CNN poll showed that 47% of Americans said they were likely to vote for Bush, and 48% said they would not; 79% of Republicans said they believed he was a president you could trust, 75% of Democrats said they thought he wasn't; 68% of Democrats believed he had been "too quick to interject his own moral and religious beliefs into politics", 67% of Republicans believed he hadn't. Break down the response of almost any question along party lines and the nation appeared irrevocably split - separate in outlook but roughly equal in size. Bush did not create these cleavages. Indeed, he had to steal the 2000 election because of them. But he had clearly exacerbated them.

To the foreign ear, while the opinions of these two camps differ sharply, they share the same tone and tenor of debate. I have found liberals in America every bit as bombastic, preachy and doctrinaire as conservatives. Patriotism, meanwhile, infects the entire culture. Doves are just as anxious to display their flag-loving credentials as hawks. Many peace activists are happy to sport "Support the Troops" bumper stickers on their cars and anti-war demonstrators carry banners saying "Peace is Patriotic", "Love my country, fear my government" or "Peace is the American Way". And the left is every bit as capable as the right of infantilising the American public with the claim that they are being duped by extremists and are therefore incapable of discerning their own interests.

But if the styles often seemed eerily similar, the substance could not have been more radically different. With no common ground and even the most basic facts polluted by partisan enmity, it was at times difficult for even the most basic conversations to take place. At an impromptu Moveon.org meeting near my home in Brooklyn, I raised polling evidence suggesting that the Democratic presidential hopeful John Kerry had to reach out more to his base, only to be told that we couldn't trust polls because they were run by corporations. Likewise, the issue of lack of weapons of mass destruction and the deteriorating situation in Iraq were, if the right were to be believed, the products of a conspiracy of disinformation by the "liberal media".

"You'll never convince me that there's no connection between Saddam Hussein and al-Qaida. Never," said Kephart, who lost his son Jonathan in Iraq.

"What is the connection?" I asked.

"Terrorist activity," he said.

This dislocation between left and right, fact and fiction, became most apparent during the 2004 presidential election, which the pollster John Zogby had branded "Armageddon election" - "Each side predicts the end is near if the other side wins."

In the six weeks before polling day, I drove from Boston, home of Kerry, to Midland, Texas, where Bush spent much of his childhood, stopping off in swing states along the way. Schlepping through the suburbs of Derry, New Hampshire, on a hot Sunday afternoon in September, I got a whiff of this impending apocalypse. Armed with water, granola bars and talking points, I followed Pam and Patrick Devaney as they went to seek out progressive voters. Derry was a swing town in a swing state and the Devaneys were reluctant but determined novices. "I'm not comfortable doing this, but it has to be done," said Pam. "Our democracy is at stake. This is the most important election in my lifetime."

Just 10 days later, I met the Kephart family in Oil City, Pennsylvania. The Kepharts were fundamentalist Christians and, for them, Armageddon was no metaphor. "I fear for this country if Kerry wins," said Burton Kephart. "God has a plan for the ages. Bush will hold back the evil a little bit. He is a God-fearing man. He believes in praying to a God who hears his prayers. He's a leader."

Little more than a week after that, I watched the third presidential debate with about 40 students in Iowa City. The Republicans sat on one side and the Democrats on the other. Sometimes, the Republicans would cheer at a phrase or facial expression of one of the two candidates, and the Democrats would look bemused. A few minutes later, the Democrats would do the same, leaving the Republicans similarly confused.

They were not just watching the candidates on a split screen. They were viewing the entire event as though from a split screen, each side hermetically sealed from the other. That summed up my trip thus far. Back in New Hampshire, Rick Sapareto, a Republican, said he was backing Bush because, "I'm very concerned that my boys may end up fighting a war in 15 years because we failed to take action."

Lisa O'Neill, who lived just a few minutes away, was supporting Kerry for almost precisely the same reason. "I have an 11- and a 13-year-old who could be drafted if this carries on," she said. When I called them both the day after the first debate, each one thought their side had won.

That has seemed to be how just about every event from hurricane Katrina to the war has been consumed. "National unity was the initial response to the calamitous events of September 11 2001," argued the Pew Research Centre in a report, The 2004 Political Landscape: Evenly Divided and Increasingly Polarised. "But that spirit has dissolved amid rising political polarisation and anger. In fact, a year before the presidential election, American voters are once again seeing things largely through a partisan prism."

The nature of these divisions was all too easily oversimplified as between the red and blue states, or between Republicans and Democrats, but it was far more profound and complex than that. At its heart, it appeared to be a conflict over what the country was for that did not fit easily into a binary code. Indeed, sometimes the conflicting strands seemed to exist even within the same people.

Gena Edvalson, a lesbian whose partner Jana is pregnant, says her neighbours in Salt Lake City, Utah, couldn't be nicer. "They're going to have a baby shower for us," she said. "But that won't stop them from legislating the hell out of us." The steel worker, who refused to give his name, in Canton, Ohio, who thought Bush was stiffing the working man but would vote for him anyway because of Kerry's stance on abortion. The wealthy white republican, Jude Waninski, who was a strong supporter of the Nation of Islam leader, Louis Farrakhan. The Evangelical protesters outside the Alabama supreme court waving Confederate flags and singing "We Shall Overcome" as they protested against the impending removal of the granite block of the Ten Commandments.

Trying to explain this division whenever I went back to Britain was not easy. "How can you stand living there?" was a common question to which I would usually answer: "How can you stand living here?" For there was nothing that you could say about American foreign policy that you couldn't say about Britain's. Indeed, as the US's principal ally in Iraq, Blair had arguably made Bush's foreign policy possible by making the claim that America had crucial allies easier to sell.

"At this very moment," wrote CLR James in the 1950s, "despite the enormous power of the American government, the man on whom it depends and has depended for years to give some dignity and colour to its international politics is an Englishman, Winston Churchill." More than 50 years later, the same could be said of Blair.

But while in America there was a clear and growing political opposition, in Britain that opposition was both confused and demoralised. True, Britain produced the biggest demonstration in its history to oppose the war on February 15 2003. But equally true was that, unlike those who attended the much smaller demonstration that I was on in New York, most of the people at the demonstration in London had voted for the man prosecuting the war and would do so again two years later. In America, there was hope of an electoral change (however slight in direction and meagre in difference) that energised huge numbers, whereas in Britain there was resignation that this was what we were stuck with. That was not to say that the situation in Britain was necessarily worse - simply that, in the US, there was real hope that both the domestic and international situation could be turned around, while in the UK there was mainly cynicism. This hope did find real expression during the US presidential election, but few, in fact, believed the outcome would satisfy it or repair the huge gash in the fabric of national life.

The fact that it is a big country, which, like any complicated and interesting place, is full of contradictions, is axiomatic. But it is rare to see a political culture and counter-culture so enmeshed, confused and evenly balanced (in numerical terms, at least) that it is impossible to tell which is which. It is obvious who has the power; it is much harder to work out who has the influence.

· Stranger in a Strange Land is published by Guardian Books in association with the New Press. To order for £10.99 plus p&p, call 0870 836 0749 or visit www.guardianbookshop.co.uk