GRANT PARK, Chicago - The first cheer went up just after sunset. Initial exit polls showed Barack Obama ahead in Indiana by 2,000 votes.

Barack Obama addresses 125,000 in Chicago.

It was far too early to project the state's winner let alone the overall election. But for the growing crowd of hundreds of thousands in Chicago's Grant Park, optimism was high. This was Obama's hometown in a state that traditionally votes for Democratic candidates.

Several road-side stalls were doing a bustling trade in t-shirts showing an imaginary Chicago Tribune front page for the morning after. It read "Obama Wins in Landslide."

Another t-shirt selling fast had a print of Obama's face etched onto Mount Rushmore.

The crowd of 20 and 30 something's roared with approval every time it saw itself on the big screen.

The evening's first standing ovation came when it was projected that Obama would win New Hampshire – the first battleground state to be called.

When Pennsylvania was called for Obama – cries of his mantra – "Yes We Can" rang out across the park.

Intermittent victories for McCain in Georgia and West Virginia were met with booing.

And then came Ohio. No Republican had ever won the presidency without carrying that state. When Obama claimed Ohio, the chanting began – "O-bama, O-bama, O-bama."

After that it was only a question of time. Individual state results became irrelevant. Only one announcement mattered and when it came delirium took hold of Grant Park.

Strangers embraced, several men and women began crying, the lady next to me fell to her knees and didn't stand up for several minutes.

And the loudest chant of all filled the Chicago night as "Yes we can" was replaced with "Yes we did ... yes we did ... yes we did."

NEW YORK - It's hard to escape U.S. presidential politics. As I walked onto the plane in London, the BBC had live coverage of John McCain at a rally in Ohio. When I walked off the plane in New York, CNN showed Barack Obama taking to the stage in Iowa.

New York City's allegiance seemed clear. While driving into Brooklyn I passed a crudely-constructed, red neon sign covering the face of a 20-storey apartment block. It read "Vote Obama."

Obama needn't worry about New York's contribution to his hopes of victory. The state has voted Democrat since 1988 and is fully expected to do so again Tuesday.

National polls also favor Obama but some New Yorkers are fretting about the national result.

One 30-year-old man told me he has booked a precautionary session with his shrink on November 5 should McCain win the election. "What if Obama loses? I can't bear thinking about it and yet I can't stop thinking about it," he said.

McCain supporters were hard to find in New York City. But I came close in a cab ride. I shared a journey with a jewelry store owner from Queens. "Obama should win this, as long as there isn't a terrorist attack," he told me.

"Don't get me wrong, I'm no Democrat and I love John McCain – I voted for him when he ran against Bush in the 90s – but this time around he just seems like he's saying and doing whatever it takes to be president," he said.

"America is all about progress, my friend," he continued. "And right now my employees can't progress financially and so neither can I. If McCain wins we won't progress for at least another four years."

I reminded him of the Bradley Effect - the theory that voters might turn against black political candidates because of the color of their skin.

"I just don't see it happening," he replied dismissively. "It's all about the bottom line. Obama has a better economic plan and even racists want to make money."

"You know Obama's the equivalent of Gordon Brown?" a young voice behind me asked.

"Well, he sort of is," a younger voice replied.

As the London Underground train jiggled about on its way to Heathrow airport I turned to find two boys in hooded tops. They looked about 14 years old.

"He must have been off his head picking Palin," sniggered one of the boys a couple of minutes later.

"Yeah, but she helps him and she hurts him, doesn't she?" the other said.

An elderly Indian woman, who was eavesdropping alongside me, nodded her head in agreement.

I hadn't even boarded the plane to New York and anticipation of the U.S. Presidential election was already thick in the air, an ocean apart from the States.

Never before had I experienced such interest and awareness in a U.S. election.

In 2000, some parts of the media renamed the candidates Gush and Bore.

In 2004, the Iraq war played a part in increasing turnout and reviving interest overseas.

Now, even more - young and old, all creeds and colour, in America and outside of it – know the candidates and care about the result.

And some of the unlikeliest characters, including two teenagers on the London Underground, are following every step and mis-step along the way to the November 4th vote.

If this was the mood in the UK, what would it be like in the U.S.?

One lady who was heading home to Pennsylvania gave me a clue as we waited to board the same flight. She was wearing a sweatshirt with a picture of a bra printed on its front. An image of a grinning Barack Obama stared out from the left cup. John McCain looked out from the right, looking equally pleased with himself.

I asked her which side she would be voting for and who she thought would win.

"I guess my top kinda says it all - I haven't made my mind up yet and I dunno who'll win but something tells me it'll be closer than people think."