Iowa:Remote, rural and 95 per cent white, Iowa's three million inhabitants are far from representative of the United States as a whole. However the state's caucuses next Thursday will have a bigger impact on next year's presidential election than the primaries held a month later in California and New York.
On the Democratic side, a victory in Iowa for Hillary Clinton could set the former first lady on an unstoppable course towards her party's nomination. If Barack Obama wins, he could go on to win New Hampshire five days later and South Carolina later in January, gathering enough momentum to demolish Clinton's poll leads in the big states that vote on February 5th.
For John Edwards, who has invested almost all of his resources in Iowa, winning the state is essential if he is to remain a viable candidate in the Democratic race.
Polls show that any of the three leading Democrats could win next week and the outcome could depend on who is most successful in delivering their supporters to the caucus - or even on the weather, which can produce snow and ice storms at this time of year.
Republican national frontrunner Rudy Giuliani has ignored Iowa and John McCain and Fred Thompson have run only token campaigns in the state. The contest is between Mitt Romney and former Arkansas governor Mike Huckabee, who has shot into the lead thanks largely to the support of evangelical Christians, who account for up to half of likely Republican caucus-goers.
A poor result for Romney could derail his strategy of winning big in the early states and gathering momentum to confront Giuliani on February 5th.
If Huckabee loses Iowa, his poorly funded campaign could struggle to remain competitive, even in the southern states where his support should be strongest.