Lincoln County, an hour's drive north-west of St Louis, is where Mark Twain learned to navigate the treacherous shoals of the Mississippi as a steamboat captain. It also has a proud tradition of picking winners in US presidential elections: it has been wrong only once in more than 100 years.

But this year, nothing is guaranteed. In the 2000 and 2004 elections, the 60,000 people of this rural county in the bellwether state of Missouri were enthusiastic supporters of George Bush. Today, the state is on a knife edge, with Barack Obama ahead but by only a narrow margin. Lincoln County, too, is divided down the middle.

Mr Bush's former aide, Karl Rove, used to say he could tell if a community would vote Republican by looking at the map to see if it was within commuting distance of a city and close to a Wal-Mart. That describes the town of Troy, but Tom Burkemper, a retired farmer, lawyer and leader of the local Democratic Party, believes its politics are as unpredictable as the winding Mississippi river.

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Although certain that Mr Obama will be elected president, he is not sure about Lincoln County, despite its near-unblemished record in picking winners. He recalls that Twain could never figure out the state's confusing political landscape, in which the descendants of Democrats who once owned slaves – including his own family – voted Democratic in local elections but often chose Republican candidates in presidential contests.

What seems to divide voters in Troy and its surrounding areas these days has little to do with race. If Mr Obama's colour was ever an issue, it has faded away as the economy has worsened. Local evangelical churches have done their best to turn voters away from the Illinois Senator, says Mr Burkemper, with some preachers even calling him the Antichrist. But opinion polls show that Missouri voters are far more interested in the Democrat's healthcare policies and whether their taxes will go up or down.

In the past 10 years, the population of Troy has almost doubled to about 11,000 as cornfields have been turned into housing estates and white, working-class families have moved in to get a foot on the property ladder. But things are a bit more difficult in the current economic downturn. That's how Holly Hagger finds things at her house at the spanking new Ashleigh Estates, just outside town. There are half-finished houses all around her and as many "for sale" signs as there are signs for Mr Obama and John McCain.

"We're not hurting, yet," she says, although she doesn't want to speculate about what her neighbours are thinking. "We have a rule around here, don't talk jobs, politics or religion, and we all get along just fine."

She has decided to vote Obama because of the state of the economy, even though her husband Robbie is still not fully convinced. "I keep my ear out and, from what I know, most of Troy will go for Obama," he says.

By contrast, the Hair Design Team salon is a hive of political discussion. Teri Peasel, 43, is plunging her client Ann McKinstry's head under the tap as she tells me: "I'm strongly for Obama and I feel all this talk about him not being against abortion is such nonsense. As for Obama, I feel he is for the people and he's worried about the middle classes.

"But we're not really supposed to talk politics here and I've probably lost a few clients as a result. I've even argued with my mother-in-law so much I could have spun her out of the chair."

Her colleague Kim Cannon, 27, is just as big an Obama supporter and says that, of the salon's 19 staff, only one is backing Mr McCain. "Even the owner supports the Democrats," she adds. "I think it's all about working women finally showing our opinions count. What's really interesting is that race is not an issue here any more. I really believe [Obama] has got the right ideas and people around here are really fed up with the economy being so down in the dumps."

Although the road to St Louis is still clogged with pick-up trucks and cars, there is little doubt many working families are overextended. A food charity which opens once a week to help those in need is overwhelmed. Instead of the usual 30 or so cars pulling up looking for a box of canned goods to see them through a tough time, there were 90 cars in line this week. There might have been a riot had Donald Thompson, owner of the Troy People's Bank, not come over with $3,000 in cheques to help the needy. Some of the money was from the bank and the rest from his own pocket.

"There are a lot of people hurting around here and I lived through the Great Depression, so I know a thing or two about bad times," he says. His bank has had to repossess only one property, however, because he did not take part in the lending frenzy of the past 10 years. "There was too much greed around," Mr Thompson explains, "and now we are paying the price."

Some of the banker's biggest admirers congregate every day at a table in the Landmark Café. A hand-made sign overhead says the "College of Knowledge" and members of the informal club are, for the most part, retired.

Some are millionaires, having made their fortunes developing shopping malls outside the town. Others are retired blue-collar workers, living on pensions that have collapsed along with the stock market. All are white and they include a handful of bigots who don't mind using racist terms when talking about Barack Obama. But, yesterday at least, they were evenly split in a straw poll. Their self-appointed spokesman is Gene Tucker, a retired Teamster union member who drove trucks for years. That was before he started his own landscaping business, which he has since sold. His political views could have come from a Mississippi swamp. "I grew up in a mixed neighbourhood and let me tell you I have never met a black man I could trust," he declared as his friends looked away in some embarrassment. A quick vote around the table revealed more Democrats present than Republicans, although some "Democrats" said they were voting McCain this time. The result was four Democrats and five Republicans with two still undecided, which is probably how the entire county feels.