Drive the multi-lane highways of Los Angeles or the mean streets of New York and it's hard to imagine an America that’s free from constant traffic. But the open road is out there to enjoy – you just need to know where to find it.

From cross-country Cannonball runs to back-country drives, from drive-ins and diners to motels there is nothing quite as American as a road trip. Except maybe apple pie.

It was a monumental feat of engineering, employing 18,000 men over an astonishingly short eight months, in some of the most inhospitable terrain the world has to offer.