In the US presidential election, the state of Iowa is kind of a big deal.

Key points: The Democratic primary officially begins with the Iowa caucus on February 4

The Democratic primary officially begins with the Iowa caucus on February 4 The candidate with the most state delegates will run against Donald Trump

The candidate with the most state delegates will run against Donald Trump The US presidential election will be held on November 3

As the first state to hold a contest in the race for the White House, it has the power to deliver one of the most potent weapons for a candidate: momentum.

That is why the Democratic caucus event on February 4 is being watched so intensely.

Historically, the winner in Iowa has gone on to seize the Democratic party nomination in seven of the past nine contests.

That means whoever wins Iowa on Tuesday will be in a strong position to be chosen to take on Donald Trump in the November election.

Surpassing expectations is also important.

Just ask Barack Obama.

From relative obscurity in 2008, Iowa put the then-senator firmly on the presidential map.

Barack Obama's surprise victory in the 2008 Iowa caucuses gave him the momentum to beat Hillary Clinton for the Democratic nomination. ( Reuters: Keith Bedford )

In fact, had he not won this state, he would never have become president, according to Rachel Paine Caufield, a Professor of Political Science at Drake University in Des Moines.

"[Iowa] really catapulted him into the race and demonstrated [his] viability and credibility on the campaign trail," she said.

"Obama brought in a tonne of money after that and people started taking a second look at his candidacy and that ultimately led him to the White House."

Pete Buttigieg grilled pork during the Iowa State Fair, a crucial campaign stop for Democrats vying to be the nominee. ( Reuters: Eric Thayer )

But Iowa is not America.

For a start, it is small, controlling only 1 per cent of the party delegates whose votes will decide the nominee at the Democratic Convention in July.

Its population is also older than average and very white.

A lot of campaigning in Iowa takes place in private homes. Here, Elizabeth Warren speaks to women in a house in Des Moines. ( Reuters: Brian Snyder )

Around 90 per cent of Iowans are Caucasian, compared to around 61 per cent for the rest of America.

"Demographically, Iowa is not representative of the United States," Professor Paine Caufield said.

The disparity has prompted calls for Iowa to be stripped of its "first in the nation" status.

Black Iowans say they miss out on the state's power

In a room that looks every bit like a high-end store for business suits, Dwight Jackson helps clients find new outfits.

Himself splendidly dressed in a grey suit, complete with waistcoat and pocket handkerchief, Mr Jackson gives everything away free of charge.

Iowan Dwight Jackson is supporting Joe Biden in the Democratic primary. ( ABC News: John Mees )

He is part of a program in Des Moines aimed at helping disadvantaged members of the community find suitable clothing for upcoming appointments, like job interviews.

Most of the clients are African-American, who do not typically engage in the political process.

Mr Jackson believes that is because they are often forgotten by political leaders who are busy serving the rest of the overwhelmingly white community.

"The only time [politicians] actively interact with the minority communities is during the political campaigns," he said.

"It's very difficult to pledge an allegiance when you seem to be an afterthought."

That sentiment is exacerbated by the extreme disparity between black and white communities here.

In 2016, Iowa's capital, Des Moines, was named the 11th-best place to live in the United States, according to a report by the Economic Policy Institute in Washington.

The state of Iowa wields enormous political power because it is the first to vote in every presidential primary. ( Reuters: Ivan Alvarado )

At the same time, it was ranked as the third-worst city for African-Americans.

Mr Jackson believes engaging in politics is the most effective way to close that gap.

"Not voting is not an option," he told the ABC.

For the Iowa caucus, he will be standing in former vice-president Joe Biden's corner.

"He's benefitting from president Obama's legacy and hopefully he'll still carry on at least the concerns that impact people of colour," Mr Jackson explained.

How Iowa's Hispanic population could change everything

Across town, stomping through snow-covered front yards in suburban Des Moines, Michael Sayman had a spring in his step as he knocked on doors.

Michael Sayman bought a plane ticket to Iowa from California to convince voters to go for Bernie Sanders in the caucuses. ( ABC News: John Mees )

The fresh-faced 23-year-old bought a plane ticket from California to focus on a group of voters that are being targeted here, perhaps like never before: Hispanics.

"The Latino vote could very well determine the outcome of this election," he said.

Latinos and Hispanics today make up 6 per cent of the state's population, a 130 per cent increase since 2000.

That is a big number, when you consider only 16 per cent of eligible Iowans took part in the 2016 Democratic caucuses.

And with such a crowded Democratic field, Mr Sayman believes a relatively small number of votes could turn the result in favour of his preferred candidate, Bernie Sanders.

"I've gone around here in Iowa to some of the Latino supermarkets and some of the stores and restaurants," Mr Sayman said.

"I tell them about Bernie and they say, 'yep, he's my guy. I'm going to make sure to vote'."

Mr Sayman has quite a tale to tell them.

Michael says he became a Bernie supporter after he got rich from designing apps and decided the system was rigged. ( ABC News: John Mees )

At the age of 12, his parents fell victim to the global financial crisis, losing their business and home in the process.

To help out with the bills, he started coding and selling apps, a venture that proved wildly successful.

"I started making a lot of money, more money than I had ever seen in my life," he said.

As he entered the top tier of income earners, he started being offered zero-fee bank accounts and even free trips overseas by businesses seeking him out as a customer.

His family could have used that sort of help when they were struggling to pay the bills.

That was when he concluded the system was rigged.

"Having entered this super-high-income bracket, I realised what Bernie is saying is true," he said.

Which Democrat will get the Iowa bump?

According to recent polls, Bernie Sanders and Joe Biden — both white and born during World War II — are the leading candidates.

Joe Biden poses with a supporter's dog after a stump speech in Waukee, Iowa. ( Reuters: Carlos Barria )

When the field of Democratic candidates was first announced, many among the party faithful were impressed by the diversity of backgrounds on offer.

But many of the early casualties have been people of colour, including Kamala Harris, Cory Booker and Julian Castro.

Cory Booker, Julian Castro and Kamala Harris have dropped out of the race, leaving an all-white field. ( Reuters )

In the minds of most Democratic voters, the issue of diversity has taken a back seat to the only thing that matters to them: who has what it takes to beat Donald Trump?

At a rally for Joe Biden in Waukee, that sentiment was clear in the thinking of Charles Hooper, who has been a farmer in Iowa since he was 21.

"This is the first caucus I'll ever go to," he told ABC.

"I'm 83 years old but we need to get this man out of office. He's ruined the country."