It's the most powerful job in the world and in November this year, we'll know who is destined for the White House and their place in history as the next president of the USA.
Watch Bill Turnbull's full series
The next step in that process comes this weekend, when the Democrats hold their Convention, to confirm the party's choice of candidates in the presidential elections.
They' the opportunity to vote for presidential and vice presidential candidates, they're also similar to the UK party conferences.
Breakfast's Bill Turnbull has been back to his old stamping ground, in the USA, for our special series on the race for the White House
Wednesday 21 July - How does the American election process work?
They say to know America you have to know baseball. So Bill went to the home of Babe Ruth, the Baltimore Orioles, to find out about the American election process at work.
Of course, all roads lead back to Washington DC, so he enlisted the help of the political director at ABC News in DC to explain who or what the electoral college is, and how you can win the popular vote - but still lose the Presidency.
Thursday 22 July - Nascar dads
Both Republicans and Democrats want them on their team, but it's mostly God-fearing, gun-loving, country-music twanging Republicans; also known as the 'Nascar dads' because they love to watch stock cars race round a track for hours at a time.
Bill joined one family in the 'infield', where they parked their mobile home for a week to enjoy the race, and find out what being a Republican means. Basically - they love George Bush, support the war, and want to pay less tax.
Friday 23 July - So what is being a Democrat all about?
Bill asks a radio talk show host and newspaper columnist in Boston, then he heads off to Cape Cod, where the gift shops sell "Justly married" t-shirts as Massachusetts embraces gay marriage.
Democrats hate George Bush, are against the war, and want more liberal social thinking, Bill finds, as he visits their heartland in the North East