Iowa’s role in the political process is firmly cemented by its first-in-the-nation role in choosing presidential candidates. In past decades, when Iowa was another reliably Republican plains state, that was the end of its serious role in the political process. Some are critical that an unrepresentative state, heavily white, heavily rural, with no major metropolitan areas, should play such a critical role in choosing presidents. Local political science professor Stephen G White says, “There are few minorities, no sizable cities, and the state’s about to lose one of its five seats in the U.S. House because its population is shifting.”

In some regards, though, Iowa has perhaps a better claim of being true ‘middle America’ than any other state. Geographically it sits close to the centre of the contiguous 48 states, with area, population and median income very close to the national average. It sits nestled between America’s two most iconic rivers, with the Mississippi forming its eastern border and the Missouri its western border. American Gothic, one of the most celebrated works of American art, was painted in Eldon, a little ‘city’ of less than 1,000 people in Wapello County. Further west, Madison County is John Wayne’s birthplace.

In terms of party politics, Iowa is also close to the national average, and arguably even reflect America’s deep polarisation. For all their famous niceness, Iowans have a fondness for electing cantankerous elderly politicos with defined ideological positions. For nearly 30 years, its two Senators have been the conservative GOPer Chuck Grassley and liberal Dem Tom Harkin. Iowa was knife-edge close in both of George W Bush’s elections, with W winning one and losing one. Obama won comfortably enough last time, but expect the Hawkeye State to return to its Bush-era status as a nailbiter.

The majority of Iowa’s landmass fits the Great Plains stereotype, with wide expanses of cornfields and soyabeans stretching along gently undulating hills to the horizon, interspersed with herds of cattle and pigs. Much of the state is thinly populated, with the population of Wales spread across the area of England. Crops and pasture cover almost 90% of the state. Religion is important here, and church often a centre of social and cultural life. But although Evangelicalism is growing, it is still outranked by mainline Lutheranism, Catholicism and Presbyterianism.

Rural Iowa has plenty of problems. Agricultural employment has collapsed and in the deep countryside little has replaced it. In the little towns that dot the cornfield, Walmart has often displaced a now half-abandoned Main Street. Meth addiction, although not at the levels seen in some of the mountain states, is a problem. Many young people, graduating from one of the best school systems in America, leave at 18 and never come back.

Yet Iowa boasts one of the lowest unemployment rates in the nation. Des Moines, the state’s capital and largest city, is a flourishing centre of the insurance and publishing industries and headquarters to the Monsanto agricultural biotech giant. The industrial southeast still has manufacturing jobs in abundance, and among other things is a key part of the supply chain of the resurgent American motor industry. While bottom end jobs in agricultural processing are appallingly paid and increasingly filled by undocumented migrants from Central America, at its top end, food processing provides thousands of well-paid jobs in engineering, marketing and management, especially around Cedar Rapids.

And it’s in the southeast that Democratic votes are at their most plentiful. In Davenport, Bettendorf, Cedar Rapids, Waterloo and especially in Iowa City, a liberal university town, Democratic margins pile up in the thousands, even in years when Republicans take the state. Indeed, the east of the Hawkeye State in general is good Democratic territory.

The northeast, where the plains give way to the steep hills and valleys of the Driftless Zone, is another Democratic stronghold, and a heavily Catholic area settled largely by Irish and South Germans.

The centre of the state is highly competitive, with several dozen rural counties won by Obama in 2008 and Bush in 2004 and 2000. Des Moines also lies in the centre of the state, and like most big cities has a leftward lean, although Democrats don’t always run up enormous margins here. When they do, they win Iowa. When they don’t, they can be in trouble.

The far west, which returns ‘tea-party firebrand’ Steve King to the US House, is the real Republican stronghold. Even the largest settlement in the region, Sioux City, once marginal, now has a strong GOP-lean. Republican margins are truly enormous in the far northwest, which is an area with a large Evangelical population. Mike Huckabee polled well in this area in the 2008 Republican caucuses.

Although these regional variations exist they are not absolute, Republicans post healthy votes in much of the east and Democrats in much of the west. Iowa is particularly notable for its high number of swing voters. In contrast to, say, Virginia or Pennsylvania, where elections are more about motivating solid demographic blocs to get out to vote, election campaigns in Iowa have plenty of undecideds to persuade, even in the currently polarised environment. And Iowans get plenty of chance to see most of the candidates for President up close, as they stump from small town potluck supper to suburban high school gym in the lengthy caucus campaign.

Over a third of Iowans voted early in 2008, and the totals are already higher this year, with five days to go. Democrats must build up a big lead before election day to win. Obama posted an 18 point lead in early voting last time. The best indication of what is happening this year is that registered Democrats make up 11% more of the current 2012 early voting population than registered Republicans. In a pattern that seems to be common across the swing states, Obama retains a comfortable early voting advantage, although one smaller than last time. While Republicans will argue that Independents may be favouring Romney this time, it still looks advantage Obama, and Election Day itself remains key to Republican hopes of victory in the Hawkeye State.

Polling shows Obama with only a 2.0% lead in the RealClearPolitics.com average. Iowa is a state where late-breaking undecideds really could make all the difference, although one doubts the nuclear holocaust of campaign ads currently infesting Iowa’s TV screens does much more than annoy. Nate Silver of FiveThirtyEight currently gives Obama a 79% chance of holding on to Iowa. That feels a little too optimistic to me, with that narrowing of the early vote gap, but the advantage in the heartland still seems to rest with Team Blue.