Think of the American press, and what comes to mind? JJ Hunsecker, the ruthless gossip columnist of Sweet Smell of Success, maybe. Or Walter Matthau, playing the insanely competitive editor of The Front Page, who would sacrifice Jack Lemmon’s happiness for a scoop. Or Woodward and Bernstein in All The President’s Men, pursuing the story that brought down Richard Nixon.

In Hollywood’s imagination, American journalists may be boisterous, impassioned and fearless. But, even by the loose standards of Hollywood mythmaking, this reputation does not stand up. The humdrum reality: most newspapers in the US are lazy local monopolies; the television networks underbid eachother for the lowest common denominator; and they all commit the cardinal sin of journalism, boring the audience.

The evidence?

Newspapers design headlines to bury the story. They are so laden with abstract nouns or the passive voice they could be spoofs. Try this: “Anger Raises Concern About Bush Run in '04”. And that was from the New York Times, widely thought the best of the broadsheets.

Heaven forbid that any article be interesting enough to offend some readers. Even private correspondence is enough to get a journalist into trouble. Bill Cotterell, a political columnist, was suspended from the Tallahassee Democrat for sending a rude email in response to a reader.

So slow-moving are US news businesses that they make their British counterparts look entrepreneurial. Time Out beat the Village Voice in the New York city listings market. The newest magazine category, the lad’s magazine, was pioneered by Maxim, a UK import.

And even the homegrown success stories turn out, on closer inspection, to rely heavily on borrowed talent. The hot magazine editor of the moment, Bonnie Fuller, is Canadian by origin; Tina Brown, of Vanity Fair and the New Yorker, was British. The New York Post is the greatest of American tabloids, except it is not all that American: the last two editors were British and Australian.

No surprise that American media organizations are gerontocracies. The most prestigious current affairs show, Sixty Minutes, has not refreshed its staff in decades. The average age of its five reporters is over 70. Piers Morgan was 28 when he took over the Daily Mirror; that would be inconceivable at any US newspaper.

All these criticisms beg the question: given that the US media market is the most lucrative in the world, why is the journalism not more vigorous? It depends whom you ask. The shrivelled intelligentsia bemoans the poverty of public-service broadcasting; liberals cite ownership by media conglomerates; conservatives blame consistent liberal bias, and suffocating political correctness; and hard-scrabble reporters the pernicious effects of ethics courses at modern journalism schools.

The underlying cause is prosaic. The United States sprawls across a continent, its population is more dispersed than that of the UK or France, and its media market is geographically fragmented.

Britain is one national market, in which a dozen national newspapers compete furiously for readers, talent and scoops. There's powerful pressure to hype up the story, which makes for more interesting copy, even if sometimes it prompts a rush to declare massacres and crises, and retract more discreetly once the facts are known.

The US has many more daily newspapers, but each serves a local market, in which it is typically dominant. Even in cities with two titles, competition is usually constrained by ‘joint operating agreements’, under which the papers share printing and distribution. And these newspapers share the qualities of all monopolies: arrogance, complacency, and disregard for the customers.

There is hope. The US news business may still be stodgy, but not for all that much longer. For which, thank technology, the introduction in particular of digital cable systems and the internet, which have opened up the market to a host of new competitors with national reach.

The cable news networks – CNN, Fox News, MSNBC and CNBC – now attract more viewers in the course of a day than do the network news broadcasts. Fox News, with fast-paced top-of-the-hour news and hard-hitting political talk shows such as O’Reilly, has displayed the most dramatic growth: founded by Rupert Murdoch in 1996 when the industry said there was no room for a new news channel, Fox News has overtaken all its rivals.

It appeals even to viewers who reject its generally conservative political bent. “Fox isn’t in any conventional sense ideological media,” says Michael Wolff, the media commentator. “It’s just that being anti-Democrat, anti-Clinton, anti-yuppie, anti-wonk turns out to be great television.”

The experience of cable television has been mirrored in internet media. Back in 1998, the story of Bill Clinton’s affair broke on the Drudge Report, an internet news site now viewed more than 5m times each day. Drudge has been joined by a host of other guerrilla commentators writing in small sites called weblogs.

The political weblogs, like Fox News, talk radio and other insurgent media, lean to the right. More importantly, they often display a nose for the story that the traditional media has lost.

When Trent Lott, the former Senate Republican leader, went misty remembering the segregationist politics of his youth, the Washington press corps ignored the story. It was the drumbeat of criticism in the weblogs that kept the controversy alive, long enough to force the mainstream media to pay attention. The new news media is raucous, sloppy and amateurish. But it is at least, at its best, engaging.

It took until the passage of civil rights legislation in the 1960s for the US to bring substance to the belief that all men are created equal. Surprising as it may seem, another element of the American constitution – a vigorous press – has been an empty letter. Until recently. At last, US news media is catching up with the myth that surrounds it.