A trip through the North American mountain range shows magical landscapes and experiences

We are at the start of our much anticipated Great American Road Trip, a great loop north from Denver all the way up to Montana and back. "Welcome to Denver, Sir," says the car-hire man. "Have you considered upgrading your small family car to this ..." He points to a photo of a supercharged, sports utility beast and adds innocently: "What if you run into a moose, or a grizzly? You'll want the extra clearance - to protect your family."

We have just staggered off the plane and here it is: America. Moose. Grizzlies. Family.

Colarado

An hour later we are out on the interstate going the wrong way around Denver in the 4x4 beast. Eventually, we turn down a track into the trees and come to the ranch house. Our cabin is next to a roaring river, which we cannot see.

At dawn I stumble out into the mountain air, blinking at the sight of hummingbirds flickering away from the flower baskets on the stoop. There's forest, river and mountains, all revealed with a clarity of vision that is breathtaking. It feels like we entered a long dark tunnel at Heathrow and emerged, slightly startled, in the Rockies. It's one of the best feelings travel has ever given me.

After breakfast, we hit the road, winding up and up towards the Rocky Mountain national park.

We bought a road atlas in Loveland, the Rand McNally large scale, and I'm reading the place names: Rifle, Sunbeam, Severance, Never Summer. All the poetry and practicality of pioneering is in those names. I wish I'd bought it long before arriving. Now we motor up Highway 34 towards Estes Park (visitestespark.com), the gateway town for the Rocky Mountain park where the Trail Ridge Road is a stunner.

Having left the park behind, we stop a night in Elk Creek then cut westwards. At a tiny town called Yampa we buy food and get some vague directions up a dirt track that takes us to Flat Tops Wilderness: a wonderful area of pines, crags and low valleys where eagles are hunting. It is magical and mesmeric, but also the wrong road and, after an hour, comes to a dead end in deep forest. I turn off the engine and a hummingbird darts through the open window hovering in front of my nose. I hold my breath until it thrums away.

Back at the main road we discover a second dirt road which proves more successful.

Wyoming

By sunset we are rolling through skeletal country that leads to Rock Springs, Wyoming, a bona fide fracking boomtown.

The next day we motor north and the mountains rear up, getting more magnificent until we hit Jackson Hole, a pretty town where young men on the streets hand out Sotheby's catalogues advertising multimillion dollar log cabins in the wilderness. Back country living doesn't come cheap around here, but we hook up with Jason from Jackson Hole Wildlife Safaris who gives us a wildlife tour to remember. "Let's get on the dirt roads," says Jason, "Best-kept secret in America." Twenty minutes later, on a dirt track outside town, I point to a large dog that's watching us from a bluff. "That's no dog," says Jason, "It's a wolf."

Grand Tetons park seems to have plenty of visitors, but it's nothing compared to Yellowstone, its immediate neighbour to the north which we reach a couple of days later. The grizzlies we spot are no danger to us: there are simply too many other cars and people in-between. To get away from the crowds and enjoy the natural beauty, you need to leave the car and walk. When we do, taking one of the trails, we don't see a soul and I wish we had brought kit for a night out in a camp.

The following day we reach Cody, worth visiting for the superb Buffalo Bill Museum.

From Cody we head north up Highway 296, a beautiful drive that brings us to the foot of the Beartooth Pass, the highest public road in the northern Rockies at almost 11,000 feet. We cross into Montana where we spend a couple of weeks visiting rodeos and staying in a log cabin, but eventually it's time to take the road back to Denver (back in Colorado), this time on a route that skirts the eastern flanks of the Rockies. By lunchtime on the first day we reach a small Wyoming town called Meteetse and we're looking for some food but are desperate to avoid the awful chain restaurants that proliferate America's roads. Fortunately there appears to be only one place open and it is not a chain. We park and enter. The Cowboy Bar has an ornate wooden bar on the right, a piano to the left, and tonnes of memorabilia on the walls. There is also a huge bear of a man sitting in a wheelchair who turns out to be Big Jim, the owner.

"There's 45 bullet holes in these walls," he says. "The boys do get bored." He tells us about Butch Cassidy, who drank here regularly. Coffee and food appears, then whiskey. We play pool and listen to stories of Kid Curry, Buffalo Bill and the Hole-in-the Wall gang - all former customers. Some cowboys come in.

Over our last few days we explore back roads through an America that's waiting to be turned into an open-air museum: clapboard barns and shuttered diners, abandoned drive-in liquor stores and original pioneer dwellings. On the Lincoln Highway, a great route to explore, we come across the ghost town of Bosler, where rusting 1930s cars lie buried in the grass and a bristling elderly man, the sole resident, shouts: "Git off my land!" It'll be a museum one day, but over his dead body.

Just beyond the lovely Medicine Bow National Forest we spend a last memorable evening in the perfect cowboy diner: the Bunkhouse near Cheyenne - and then it's over. The trip has been incredible, giving us access to landscapes and experiences we never imagined, nor did we ever get tired of driving. We would keep on going if we could, gripped by the hypnotic magic of the ever-changing land. — © Guardian Newspapers Limited, 2014

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