The United States is the size of a continent: it is therefore pointless trying to make any sort of dent into the amount of possibilities on offer to the walker in this guide as you can - quite literally - find anything here. In terms of a tour of terrain, beginning in the south west you have the arid canyons and desert mountains of New Mexico, Southern California and Nevada. Moving to the south east you have the swampy, vegetated states of Alabama, Florida and Mississippi. Across America's northern longitudes, you begin in the west with the coastal volcanic ranges of Oregon and Washington, working your way high into the Rockies of Colorado, Montana and Utah, dropping into the largely flat central plains (dusty in the south, wet and green in the north) before discovering the country-spanning eastern ranges of the Appalachians towards the east. Then of course there are the peripheries: Hawaii, with its splendid, jungly volcanic terrain, and a gentle little place up in the far northwest called Alaska. The American walking culture has a huge following, be it simply for 'car hikes' (park the car and walk from it in a loop) or extended backpacking trips. The National Parks here have got their heads screwed on when it comes to preserving their natural splendour, and while some have slightly stiff rules and regs when it comes to what you can and can't do in the backcountry, the crowd control evident in some places (such as Alaska's Denali, which issues permits for backcountry wanderers) is quite often geared to give the walker even more of a pristine experience there. Which can't be bad.

What you do in America really depends on how much time you have. Starting big, three immediate enticements spring out which serve as handy threads which tie together much of America's grandeur - and will do their damnedest to show you as much variation as possible: the Continental Divide Trail, the Pacific Crest Trail, and the Appalachian Trail. The latter two are long-established stomping paths which bisect the USA in hugely entertaining fashion, whereas the Continental Divide Trail (CDT) is a slightly more intermittent, much more ambitious trail which is growing in popularity year-on-year. Make no mistakes, these are big trails in every sense: The Appalachian Trail is the most popular, requiring 2,186 miles of walking over mountains and through forests from Springer Mountains in Georgia to Mount Katahdin in Maine - more or less the entire eastern extent of the USA, vividly described in Bill Bryson's A Walk in the Woods - to become a 'thru-hiker', as completers are known. Those who don't have several months to do the whole thing choose to pick off selected chunks in one of the Appalachian's many standalone attractions, such as the awe-inspiring Great Smoky Mountains National Park, the remote Blue Ridge Mountains, the comely Shenandoah hills, the heavy forests of the Adirondacks or the Hundred Mile Wilderness of Maine, which is every bit as easy and accommodating as it sounds. Whatever level of challenge you're after, you'll find it on this trail. For those who want even more of a challenging day out, the Pacific Crest Trail is perhaps more your thing, oscillating jarringly over some of the Rockies' most demanding terrain as it winds its way north 2,600 miles from Mexico to Canada via California, Oregon and Washington. Both of these trails are well-waymarked, and come with a series of rudimentary shelters of ropy repute, and usually frequently (though often not) peppered with blips of civilisation which allow restocking, refuelling and rehydrating. The CDT stretches through 3,100 miles of the mid-west, from New Mexico, through Colorado, Wyoming, Montana and Idaho, touching on the greatest outdoor features of America en route to user-defined levels of severity. All are fine ways to spend upwards of six months, and unbeatable ways to experience America's enviable outdoor variety.

In terms of individual areas, as mentioned, choosing is difficult given the sheer variety of outstanding, unique attractions on offer. To give a microcosm of the most outstanding is probably the following. If you're in the North West, Glacier National Park in Montana and Yellowstone National Park in Wyoming are fairly convenient to link, combining a park rammed with some of the Rockies' most astonishing scenery with the beautifully veneered, simmering volcanic menace of one of the world's most famous attractions in one trip. Further west, the Cascade range is a rainy wilderness of forested volcanoes and mighty rivers, including Mount Rainier - the highest peak outside of Alaska - and the ill-fated Mount St Helens. If you're in the south west, a trip to the Grand Canyon, Monument Valley and Bryce Canyon in Utah, or walk some desert trails in New Mexico. Then there is California, home to the Sierra Nevada (home to the 30-day John Muir Trail), Joshua Tree National Park, Death Valley and Yosemite, where you can walk to the top of Half Dome and look over the edge of one of the world's most famous vertical drops (yes, it is that sheer up close) or check out the climber's on El Capitan. In the East, the Great Smokies, the pristine wilderness to the east of Lake Superior and the endless, surprisingly mountainous forests of Maine each offer enough to keep you entertained. The South East is famous for its rivers, amongst other things (seen Deliverance?) and for those who like their danger, the Anhinga Trail in Florida's Everglades National Park offers the chance to get up close and scared with alligators. And if you want it wild and cold, trek a glacier in Alaska's Kenai Fjords National park, take the ferry across Prince William Sound then head north to Denali National Park, book a backcountry permit, walk in and and stare at Mt Mckinley - one of the Seven Summits and a monster to behold - before turning round in all likelihood to find a Grizzly Bear looking curiously at you. England may have the Lake District. But there's no denying it: America's got the lot.