6. Shenandoah National Park

Just 120km from bustling Washington D.C., Shenandoah National Park is a popular retreat for city-dwellers, who come to enjoy its gushing waterfalls, sun-streaked forests and fresh, mountain air. A highlight of the park is Skyline Drive, a 170km-long road that runs alongside the Blue Ridge Mountains. It is most spectacular in the autumn, when the surrounding trees are changing colour most dramatically.

7. Voyageurs National Park

The name of this park, in the heartland of the United States, refers to the French-Canadian fur traders, the first European settlers to make numerous journeys through the region. With its four large lakes and extensive web of waterways, the park encompasses a vast amount of water, making it a very popular area for canoeists, kayakers and fishermen.

8. Yellowstone National Park

The first ever national park, Yellowstone needs little introduction. A stunning collection of geysers perform dizzying spectacles with boiling water, while moose, wolves and bears traverse the mountain ridges above. At the heart of the park lies Yellowstone Lake, which sits over the Yellowstone Caldera, one of the largest active supervolcanoes in the world today.

9. Zion National Park

A red-and-tan labyrinth of canyons, mountains and monoliths, Zion National Park in Utah is a major rock-climbing and hiking destination, offering many well-established routes of varying difficulty. At the heart of the park is Zion Canyon, a spectacular gorge plunging 800m and 24km across.

10. Glacier Bay National Park

Glacier Bay was first surveyed in 1794, sporting just a small indentation in the ice. By 1879, though, conservationist John Muir recorded that the ice had retreated 30 miles, creating an actual bay. The area was later put under the protective moniker of national park and today is a favourite stop for cruise ships, which come to its glistening icy landscape and snow-laden mountain peaks.

11. Grand Canyon

An immense, jagged wilderness, Arizona’s Grand Canyon National Park is one of the world’s most popular natural attractions, with nearly five million people visiting each year. Its central feature is its vast canyon – a vivid sunset-blend of red, yellow and orange sedimentary rocks – stretching 29km across, 446km lengthways and plunging 1.6km downwards.

12. Grand Teton National Park

Wyoming’s Grand Teton National Park joined to Yellowstone National Park by the J.D Rockefeller Jr. Memorial Parkway, boasts a pristine ecosystem of alpine peaks, clear blue lakes, shady forests and large number of black and grizzly bears. The park’s Snake River is celebrated among fishermen, who come to try and catch the fine-spotted cutthroat trout.

13. Great Basin

A swathe of desolate, dry and mountainous desert land peppered with groves of ancient bristlecone pines, Great Basin National Park sits 470km north of Las Vegas in Nevada. At the base of the highest mountain, Wheeler Peak, are the impressive marble Lehman Caves (visit by guided tour), ridden with spiny stalactites and stalagmites.

14. Great Smoky Mountains

This park – affectionately known as the Smokies, for its lingering early morning fog – wins the prize for being America’s most visited park. Straddling the border between Tennesseeand North Carolina, the park has over 1000km of walking trails up and over its pointed peaks as well as eastern America’s largest population of black bears and remnants of South Appalachian mountain culture.

15. Guadalupe Mountains

Encompassing Texas' highest peak, Guadalupe Peak, the Guadalupe Mountains have a fractious and turbulent history, witnessing ferocious battles involving local Apache tribes, Buffalo Soldiers, European settlers and ranchers. One such European settler, Felix McKittrick, has a canyon named after him, where in the autumn Bigtooth maple trees metamorphose into a riotous blaze of colour.

16. Gunnison National Forest

Over two million years, the Gunnison River has carved out a spectacular canyon in western Colorado – the so-called Black Canyon. Diving an average of 5 metres per kilometre, the canyon is the fifth steepest descent in North America. As most of the rock-climbing here is for advanced climbers only, visitors generally come to drive around the southern rim of the canyon for magnificent views down into the shadowy gloom.

17. Haleakala National Park

Along with its beautiful rainforests harbouring numerous endangered species, the highlight in Maui island’s Haleakala National Park is its dormant volcano, whose enormous crater attracts daily sun-worshippers who pound to the top of the ridge for mesmerizing views of both the sun rising and setting. Once the sun has disappeared, the telescopes come out: with its extraordinarily clear night skies, Haleakala is one of the best places for amateur astronomy.

18. Isle Royale National Park

Isle Royale is the largest island in Michigan’s Lake Superior, stretching 72km in length and 14km across. Accessed only by boat – usually the sizeable Ranger III ferry – the island has one of the largest wolf and moose populations. Hikers tend to attempt the 60km-long Greenstone Ridge Trail, while there’s plenty of diving and kayaking opportunities for water babies.

19. Joshua Tree National Park

A predominantly rock- and scrub-strewn wilderness covering two deserts – Mojave and Colorado – California’s Joshua Tree National Park is best known for its namesake plant, the Joshua Tree. These gnarled, contorted trees are indigenous to the higher-altitude, cooler Mojave Desert. Vegetation aside, Joshua Tree National Park is an ardent favourite among campers, hikers and particularly climbers.

20. Kenai Fjords

Although it can be accessed by car (via Seward), Kenai Fjords National Park – home to the largest icefield on the planet, the Harding Icefield – is a popular pitstop on a cruise round Alaska. It’s certainly worth the sojourn, for the wonderful views of jagged and beautiful fjords (created by colossal glaciers slipping down mountain sides) as well as of sleek sea lions, porpoises and orca whales sliding through the waves.

21. Kings Canyon

Twinned with Sequoia in the southern Sierra Nevada, Kings Canyon National Park was created in 1940 with the express purpose to protect the General Grant Grove of giant sequoias. And it’s not just the trees that are on the bigger size here; the park also has immense mountains thrusting skywards as well as deep, dark canyons and huge, gaping caverns.

22. Lassen Volcanic National Park

A steaming, smoking stretch of volcano-laden land in northeastern California, Lassen Volcanic National Park was, after a series of violent eruptions, created to protect local residents as much as to protect the land. The focal point of the park is the largest plug dome volcano in the world, Lassen Peak, while Bumpass Hell is an exhilarating boardwalk trail round bubbling mudpots, boiling pools and hissing fumaroles.

23. Mesa Verde National Park

Some of the oldest human dwellings in the world are protected by Colorado’s Mesa Verde National Park – which, in Spanish, means “Green Table”. The sturdy dwellings were carved into cliff faces by Ancestral Pueblo people between AD 600 and 1300, and “Cliff Palace” is the daddy of them all – the largest cliff dwelling in North America.

24. Mount Rainier National Park

Of the total number of hikers who attempt to summit Mount Rainier, the 4390m-high glacial volcano in Washington state, only around half make it. It’s a tough climb, with the peak often shrouded in swirling, rain-sodden cloud. The rain is responsible for spring’s spread of wild flowers around the volcano’s rim and forested flanks.

25. Death Valley National Park

Sitting below sea level, Death Valley is the lowest and driest place in North America, and the hottest spot on the planet, its temperatures reportedly reaching 56ºC/133ºF. With measurements like these, supported by its morbid name, it’s surprising to find that the valley is home to an array of wildflowers, fish and animals such as coyote and roadrunners. Despite its low depths, the valley also sports ice-covered tips around its basin – it certainly covers the extremes.

26. Denali National Park

A massive six million acre park with the equally massive Mount McKinley standing proud and tall in the centre, Alaska’s Denali National Park comes into its own during the winter months, when snow and ice brings opportunities for dog-sledding, skiing, snow-shoeing, snowboarding and snowmobiling.

27. Dry Tortugas National Park

An enormous, unfinished coastal fortress constructed – and never fully completed – during the nineteenth century, Fort Jefferson sits in the middle of Dry Tortuga National Park in the Florida Keys. Today, boasting incredibly clear waters and a terrific mix of tropical marine life, the area is a haven for scuba-divers and snorkellers.

28. Everglades

A complex ecosystem combining coastal swamps, estuarine mangroves and sawgrass prairie fields – to name but a few – the heart of Florida’s Everglades National Park can only be accessed by boat or canoe. There are hiking trails around some of the islands but these require a decent pair of wellies and a strong nerve – the ‘glades are home to plenty of beasties such as alligators, snakes and spiders.

29. Gates of the Arctic National Park

The northernmost park in the US, and approximately the size of Switzerland, Gates of the Artic National Park is virtually untouched by man. There are no rail lines or roads in the park, only barren mountains, vast wild meadows, meandering rivers, migrating caribou and captivating skies lit up by dancing aurora lights.

30. Congaree National Park

Most visitors to South Carolina’s Congaree National Park come to walk along the Boardwalk Loop, a 4km trail that penetrates deep into the dark floodplain forest, which makes up the largest tract of old growth bottomland hardwood trees in the US. The park was named after the American Indian tribe who lived here until the 1700s, when they died out following a smallpox epidemic brought over by European settlers.

31. Crater Lake National Park

The name gives it away: the deep, dark blue lake in Oregan’s only national park occupies a large caldera, the remains of a now dormant volcano. There are no rivers or streams running into or out of the lake, leaving the water crisp and breathtakingly pure. Trout- and salmon-fishing is a popular pursuit here, as is hiking and camping in the surrounding forests.

32. Canyonlands National Park

A chaotic, colourful wilderness of canyons, buttes and mesas, in southeastern Utah has been eroded and shaped over the years by the mighty Colorado and Green rivers. The park is split into four areas – the Island in the Sky, the Needles, the Maze and the rivers themselves – each one offering plenty of sporting activities, such as kayaking, rafting and mountain biking.

33. Capitol Reef National Park

The Waterpocket Fold, a spectacular 65 million year old wrinkle in the earth’s crust is enclosed in Utah’s Capitol Reef National Park. It’s a rugged and arid mêlée of cliffs, canyons, ridges, arches and monoliths that provides a dramatic backdrop to hikes, horseback rides and driving tours.

34. Carlsbad Caverns National Park

Discovered in 1898 by intrepid teenager Jim White, the enormous Carlsbad Cavern is the main attraction in Carlsbad Caverns National Park in New Mexico. There is a hiking trail to the cave, or an elevator straight there from the visitor centre.

35. Channel Islands National Park

Of the eight Channel Islands off California’s coastline, five are protected under national park status. Despite being relatively close to the people-packed mainland, the islands have remained surprisingly isolated and undeveloped. It’s mostly water-based fun here: the complex Sea Caves attract plenty of kayakers and spear-fishermen, while in the winter months, migrating gray whales draw their own hefty fan base.

36. Acadia National Park

Maine’s Acadia National Park is an alluring mixed bag of beaches, ocean coastline, granite peaks, calm woodlands and rippling lakes. The park covers Mount Desert Island, the largest island off the coast of Maine, which is also home to the green, lichen-swathed Cadillac Mountain, said to be the first place in the US that is warmed by the sun’s rays each morning.

37. Arches National Park

Of the 2000 naturally formed arches in Utah’s Arches National Park, Delicate Arch is the most famous. It features on the Utah license plate and the 2002 Winter Olympics torch relay was passed through it. This arch, and its less famous siblings, are all made of livid red and orange sandstone and are particularly stunning at sunrise or sunset

38. Badlands National Park

The black-footed ferret, the most endangered land mammal in North America, calls the wild and grassy prairies of South Dakota’s Badlands National Park home. These prairies cover what was once a sea bed, and many fossils belonging to mysterious sea creatures have been discovered. There is a fascinating fossil quarry and laboratory in the park that show off the most recent finds.

39. Big Bend National Park

Big Bend National Park in Texas is one of the largest, most remote and least-visited parks in the United States. It’s the place to come for peaceful hikes, tranquil boat trips and excellent, varied birdwatching. There are many species of plant and animals here, both living and dead: archeologists have unearthed fossils dating back a staggering 9000 years.

40. Bryce Canyon

Despite the name, Bryce Canyon – in southwestern Utah – is not a canyon. It’s actually a series of bizarrely shaped, giant stone amphitheatres made up of red, orange and yellow hoodoos (thin spears of rock, also known as fairy chimneys or earth pyramids). Today visitors hike and drive to look out points around the park to watch the sun rise and set over this extraordinary, fiery landscape.