The independent and maverick values of a Hollywood version of the wild West are deliberately being evoked in the language used by the Republican Party as the candidates square up in the race for the White House. But real life is never as clear cut as on the silver screen

One easy way for perplexed observers to chart America's national mood swings is to follow the course of the archetypal American movie, the Western. Indeed, the rise of moving pictures coincides perfectly with historian Frederick Jackson Turner's declaration in 1893 that the frontier - the topography that defined the American character - was no more. For a land of seemingly boundless space and Manifest Destiny, that was like reading your own obituary, and for the past century Westerns have provided a way for the nation to channel its purer, primeval spirit: the hardy, self-sufficient pioneer, braving - and taming - the wilderness while fighting off bad guys in black hats or Indians in warpaint and, above all, the predations of East Coast civilisation that followed like wolves: greedy speculators, robber baron railroads and, of course, the federal government.

In this morality tale, the only thing standing between the forces of evil and the simple virtues of the small town frontier was a lone man on a tall horse. This paladin with a pistol may wear a star on his waistcoat or, more poignantly, he may be a gunman with a past who is redeemed by standing firm where he once would have run. "The greed and brutality that abound in our world exist because most of us lack the gumption to do battle," as Jean Arthur said on the set of the 1951 movie Shane , one of most popular and archetypal Westerns ever made - the story of an ageing, rueful gunslinger who sacrifices himself to help dirt farmers defeat powerful cattlemen. In thousands of B-movies and television series, and in dozens of films that became classics of this and any other genre, the celluloid saga of the cowboy, the Western hero, reassured Americans that justice would triumph, thanks to good men who were willing to do bad things to keep the rest of us safe. Westerns were an emotional anchor through the Great Depression, the Second World War, the Cold War, and even the turbulent Sixties.

Now, in 2008, with terrorists posing a new threat, a new sheriff walks down these dusty streets, with a faithful but fiery gal by his side, ready to take on the evildoers: John McCain of Arizona and his trusty sidekick, Sarah Palin of Alaska. So thorough is the "Westernisation" of the Republican presidential ticket that the cover of The Weekly Standard, the flagship periodical of the neoconservative right, depicted McCain and Palin as Gary Cooper and Grace Kelly in the classic High Noon. It all works (even that all-too-noticeable age difference). McCain plays up his reputation as a "maverick" - also the title of a popular 1960s TV series and a 1994 film remake - and Palin is routinely described as a pistol-packin' mama who talks as straight as she shoots and would just as soon field dress an opponent as debate him.

That was certainly the case during the debate on 2 October between the vice-presidential candidates. Palin's Democratic counterpart is Joe Biden, the senior senator from the tiny Eastern seaboard state of Delaware, and throughout their 90-minute duel Palin repeatedly underscored their divergent pedigrees by mixing tough talk and folksy charm and invoking the term "maverick" so many times, it threatened to become a verbal stampede.

Yet the paradox of all this Republican campaign hype is that the sturdy conservatism of the Old West is largely a myth, a national legend whose fictions McCain and Palin themselves represent.

Take McCain's home state of Arizona. A vast expanse of desert plains and snow-capped mountain ranges, Arizona looks like the backdrop of a cowboy movie, which it often was. The plot of the 1962 John Ford film, The Man Who Shot Liberty Valance, turned on a tense showdown over whether a large Western territory - assumed to be Arizona, the last of the 48 contiguous states admitted to the Union - should press for statehood. The black-hatted gunman Liberty Valance (Lee Marvin) terrorises the town of Shinbone in order to halt the statehood campaign, but do-gooder Rance Stoddard (James Stewart) improbably guns down the killer in a shoot-out. Stewart's character rides the fame of his deed to statehood and elected office. The conservative icon Barry Goldwater embodied this wild West culture of personal virtue and rugged individualism, as does John McCain. "Everything that was done, we did it ourselves," Goldwater boasted.

The truth is more complicated in that Arizona would not exist without generous federal subsidies. In fact, most of the West was created from free land made available through the Homestead Act of 1862, and it was protected by a huge federal military presence that cleared out Mexicans and Indians (and created a few myths of its own along the way, such as Custer's Last Stand). Government largesse even provided the foundation for the Goldwater family fortune, and Arizona still receives much more in federal aid than it sends back to Washington in taxes each year. It is the most urbanised state in the union, with nearly 60 per cent of its residents living in large metropolitan centres that are spreading like wildfire and burning up resources faster than the state can preserve them. And the economy depends on Sun Belt retirees and Mexican immigrants more than native Arizonans. Even McCain, now the state's senior senator, was the privileged son of a naval officer who was raised in Episcopal boarding schools in Virginia and didn't move to Arizona until he married his second wife in 1980.

Alaska, where Sarah Palin is governor, is an even clearer example of wilderness bravado underwritten by liberal subsidies. The state is blessed with the nation's largest domestic oil reserves, along with other precious resources, but it taxes them - and its citizens - at more than double the national average. Despite this income base, Alaska still spends far more than it takes in, and it ranks first (out of the 50 states) in money it receives from Washington (US$13,950 per citizen, according to most recent figures) compared to tax receipts it sends back (US$5,434). "The trick is that Alaska's government spends money on its own citizens and taxes the rest of us to pay for it," as Michael Kinsley wrote in Time magazine.

Moreover, for all Palin's talk of reforming Washington and reining in federal spending, as mayor of the small town of Wasilla, she secured "earmarks" - special funds quietly slipped into big federal bills - at double the rate of the entire state. From 2000 to 2003 Wasilla received an average of $6.7 million in earmarks for a town of some 7,000 residents, and yet Palin's spending still left Wasilla with a $19 million debt where it had been debt-free before she took office. Then in 2006 Palin won election as Alaska's governor in part because of her support for a federally financed $400 million "Bridge to Nowhere", an infamous (and eventually scrapped) pork-barrel project to build a huge bridge to a tiny Alaska town. The Bridge to Nowhere became a national joke and a butt of John McCain's criticism - until he selected Palin, who continues to insist that she opposed the project despite all evidence to the contrary. Overall, Alaskans receive more in earmarks - US$231 per person - than any other state. (The rate is US$22 per capita in Illinois, Barack Obama's home state.)

In any other nation, such contradictions might take a toll on a politician's reputation. But in the United States, where blue jeans are the national dress code and a B-movie cowboy (Ronald Reagan) is hailed as the real thing, the Western aura can go a long way. Moreover, the Western hero is by definition a flawed character set apart by his (or her) ability to act decisively at the critical moment. A shadowy past boosts a cowboy's credibility, proof that in a dangerous world he is willing to get dirty so we won't have to. Wyatt Earp, the sheriff and folk hero who took part in the gunfight at the OK Corral, was no saint, and Dodge City was no garden party. Similarly, the menaces in today's world - from radical Islam to Wall Street avarice - also demand a hero out of central casting. It is the ends that matter today, not the means, and the more McCain and Palin bash effete Eastern elites, the more they inspire confidence that they will do what it takes, never mind that their charges may not be true or their own records may be suspect.

Besides, it's a painful thing to rewrite a national narrative, especially in the midst of a national crisis. And a healthy dose of cognitive dissonance has always been necessary to maintain the myth of the American frontier. At the end of Liberty Valance, James Stewart's character confesses to a newspaper editor that his entire career was built on a lie - that it was the character played by John Wayne (whose real name, by the way, was Marion Morrison) and not Stewart who shot the outlaw and deserves the credit. The editor doesn't bat an eye. "This is the West, sir," he says. "When the legend becomes fact, print the legend."