Ros Atkins presented the first part of the journey, travelling all the way from Los Angeles to Dallas.
Here he reflects on the journey from LA through the Mojave Desert.
Part three: Desert heat
I'm sitting at the front of the BBC's Talking America bus - and through its enormous windscreen is the Mojave Desert in its dusty glory.
There's little out there apart thousands of Joshua trees, some guys fixing up the road and the kind of heat that had me cowering when we stopped a little while back.
All that will change soon though. We've just passed the sign saying welcome to Nevada, and Las Vegas is under 50 miles away.
It all feels a long way away from the freewheeling eccentricity and sandy expanses of Venice Beach in LA. Attitudes seem very different as well.
As the sun was losing its sting yesterday afternoon, I'd sat at the edge of water with a local family and talked about 11 September.
"I'm pretty focused on the election right now," said Deidre.
"9/11 was terrible and of course I feel bad for those who lost their lives, but that grief so many of us felt that day has been taken advantage of by President Bush."
Her husband Noel agreed . "Look Ros," he said, "I know it's the anniversary, but all I can think about is getting the Republicans out of office."
The story couldn't have been more different in Baker. More truck stop than town, it sits on the edge of death valley with its diners, take-aways, gift shops and gas stations stretching along what was once route 66.
George was eating lunch with his wife Paula, and they let me interrupt them. I'm told him what I'd heard on the beach.
"The thing is that these folks forget when the economy's bad, when they've other things on their plate - they forget how serious this is," he says.
"We've got to stay the course that President Bush has set."
As for the future, Paula said she didn't really know what Obama or McCain would do. If they'd just stopped talking about lipstick we might find out, she added.
So Las Vegas next, then Phoenix, Alberquerque and Dallas.
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Part two: Lipstick-gate
This wasn't how things were supposed to be for California's many Barack Obama supporters.
Not too long ago their man had a 10 point plus lead over John McCain and things were more or less going to plan. That was until a certain Governor of Alaska entered the fray.
When John McCain announced Sarah Palin as his running mate, the reaction of many Americans was who? There is no danger of them not knowing now.
I have spent day one of the BBC's Talking America bus tour on Venice Beach in California... and it didn't matter what questions I asked of people we met, one person's name kept coming up and it is fair to say they're not fans.
It's not so much that they don't agree with Sarah Palin's views. they just don't 'get' her, or why anyone would consider her worthy of the responsibilities of vice-president.
And then of course what is being called lipstick-gate.
The gloves are off
Talking about John McCain's policies, Barack Obama said "you put lipstick on a pig, but it's still a pig".
Its not something we say in the UK, but its a regular phrase in the US. In fact John McCain has used it before.
But the word lipstick, much like everything in this campaign has been touched by Sarah Palin.
She used it in her convention speech to describe the difference between a hockey mum and a pitbull.
Now depending on who you ask, Senator Obama delivered was a disrespectful slight, or it was nothing at all.
Almost everyone I asked as we strolled the cafes, skate shops and vast sandy stretches of Venice Beach said it was the latter.
But they were still withering about the McCain spin machine for picking it up, and then sure enough they'd move onto Governor Palin again.
If it's Obama and McCain who are in the presidential ring, two days with the bus in LA have confirmed that it is Palin's selection that has taken the gloves off.
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Part one: Getting ready for the launch
I'm at the beginning on a long journey. Well two in fact. To write this I'm taking a break from cramming BBC t-shirts and US politics print-outs into my suitcase, and tomorrow I'll fly from London to LA.
From there the BBC bus will begin its long journey east on Wednesday 10 September. With all due respect to the world's biggest thermometer in California, Las Vegas will be our first main port of call. I will be going as far as Dallas - and the bus will reach the end of the road in New York.
If all goes to plan - and it should as some great producers have put in some heavy hours on this - we'll cover 4,000 miles and pass through 15 states.
Why? is a reasonable question to ask. The answer is that the relationship between America and the world ranks up there with any issue or story we cover on the BBC World Service.
It affects us all, and my experience on World Have Your Say is that however you phrase it, if we discuss America's place in the world many of you want to get involved.
This bus trip is our attempt to paint a detailed picture of America ahead of the election in November. We also want to create conversations between Americans and everyone else which will help us all understand the role you all want for the world's most powerful country.
And I'll not being doing this all alone. Colleagues from the BBC's Persian, Vietnamese, Spanish, Arabic, Kyrgyz, Hindi, Urdu, Pashto, Albanian, Russian, French and Swahili services will all be joining at some point, as well as BBC television and the BBC News website.
We are not unaware that it's an ambitious project (there have been some sleepless nights I am told), but all being well it'll be something you enjoy listening to, watching, reading and most importantly, getting involved in.
Stay in touch.