In our travels we have noticed that many people have not visited the USA, just as most Americans have not traveled to other parts of the world.  And most of those who have visited the USA on vacation have gone to the well publicized urban destinations of New York, Miami (especially popular for Latin American visitors), San Francisco, or Las Vegas.  Yes, a great many foreign visitors do go to the Grand Canyon or Yellowstone National Parks, but very few people travel to state parks, national wildlife refuges, or Audubon Sanctuaries (for example).  This is not surprising, as even an informed tourist from another country can be overwhelmed by the plethora of internet information about the USA that is online.  See one example for birding in Florida, for example.

We quickly describe here the hierarchy of parks and reserves that occur in the USA.  The organization and status of these areas differs from nature areas in Europe or many other parts of the word, and we draw comparisons where appropriate to parks and nature reserves in other parts of the world where we have traveled.

In order from best known to least know nature parks and reserves we find in the USA the following: 1) National Parks and Monuments, 2) State Parks, 3) National Forests, 4) National Wildlife Refuges, 5) Bureau of Land Management land, 6) Private preserves.  The federal lands can be seen on USA maps like this:

or this map the US National Forests:

Overlapping some of these lands are wilderness areas and national recreation areas; these can be found in National Forests and BLM lands.  Some parts of National Parks are also designated wilderness areas.  Wilderness areas have the highest category of protection; no motorized vehicles are allowed not any vehicle roads.  Only trails for hikers are allowed.

Historically, much of the eastern US had fallen into private hands before the western lands became states and part of the US.  For this reason, most of the public lands, whether National Parks, National Forests, or Bureau of Land Management lands are in the western US.

We discuss each of these categories in turn:

National Parks and Monuments  These are managed by the National Park Service and the aim here is preservation in a natural state – no modifications of the landscape.  The webpages for any National Park can be found here.  However, to find maps of any National Park or Monument this site, maintained by one individual, is better, since all the park maps can be found in one place – more than 1700 maps! 

National Parks generally contain areas of high scenic value, though there are some exceptions, such as the Everglades, which are nearly flat.  However, there might be prescribed burns set to maintain the natural state or small road improvements or additions to lodging to improve the visitor experience.     A selection of some of our favorite NPS lands in the drier part of the southwest is shown below:

National Parks usually have entrance fees and are the most heavily visited natural areas – though some national parks or monuments in more remote locations (e.g. Death Valley National Park in summer) can be lightly visited compared with those closer to urban areas.   The official website of the National Park Service is a good place to start planning your visit to a National Park.  Here you will find information on park locations, passes, travel tips etc.  But the best site for finding maps of all of the  National Parks and monuments – in one place – is here. 

State Parks  The US has a large selection of State Parks. According to the National Association of State Park Directors (NASPD) website, as of 2014, there were 10,234 state parks in the United States!  Each state maintains a network of parks primarily funded by the state.  These may, or many not, have entrance fees.  Many parks are multi-use – that is they may have golf courses, playgrounds, camping and fishing areas in addition to natural areas and nature trails (which they may or may not have).  In many parts of the country state parks are located around reservoirs, since boating and fishing are major past-times.  In a relatively few states (e.g. Florida) the goal of the park service is to restore the landscape to its state prior to the arrival of Columbus, but this is not by any means universal.  

Some state parks can be only a few dozen or a few hundred acres in size, but the second largest, Anza-Borrego Desert State Park in southern California, is approximately 600,000 acres.  Use the NASPD website to explore by state and find relevant information about parks along your possible travel routes.

Although state parks can be crowded in summer or during holidays especially if the park in question is near a large city, in general, State Parks tend to be less crowded than National Parks.  They also are not nearly as well-known as the National Parks yet there are many state parks that offer outstanding landscapes, trails or camping opportunities.  For the foreign visitor they may be better places to see natural landscapes than the national parks, especially if you are interested in the smaller apects of nature (birds, plants, insects etc) instead of the larger landscapes and views that most national parks emphasize.

National Forests   The United States has about 150 National Forests.  These cover about 188 million acres (760,000 square km).  These areas are large tracts of, you guessed it, forested areas that are managed by the US Forest Service.  They are multi-use lands, so trees can be cut for timber or paper, cattle can be grazed on the land, and hunters (in season) are in the woods shooting anything that moves (in fairness to hunters, deer are usually abundant and go otherwise unchecked because of the lack of top predators).  In fairness to the Forest Service, only small numbers of cattle are grazed (in some forests), deer hunting is a handful of days in late fall or winter, and  the cutting of trees for timber or paper is now done mostly on private land (though selective logging still is common in the national forests).  And in recent decades a greater awareness at all levels of society has nudged the Forest Service and Bureau of Land Management (below) towards a more responsible stewardship of the land, with a greater focus on preserving biodiversity and “ecosystem functions”.

Although you may be driving through a National Forest and see houses and small communities in places, these are on in-holdings, not the actual National Forest Land.  Because of the need for selective logging in most forests, there is a large network of dirt roads through the forests – at least in the eastern US where the land is relatively flat.  These roads, most of which are suitable for normal sedan cars with care (though high clearance vehicles give more peace of mind) are excellent for seeking wildlife and flora.  This is because most are very lightly traveled (except in deer hunting season!) and you can essentially stop on the road when needed.  Here is good site to find out more about the many National Forests.

National Wildlife Refuges  Overseen by the US Fish and Wildlife Service there are approximately 560 national wildlife refuges (NWR’s).  About 500 of these refuges are open to the public with most of them not charging admission.  This network of refugees was established to protect migratory birds and waterfowl that were being hunted to extinction.  The refugees have expanded in their role over the years to support many kinds of wildlife, not just waterfowl – though a great many reserves focus on birds that can be hunted.  In fact, most refugees are not pristine landscapes, with many having large fields of grain specifically for the birds.  None the less, NWR’s are generally excellent places to see wildlife, and they usually have visitor centers and nature trails, viewing platforms and boardwalks.  

Some refuges can be very large (some in Arizona are tens of miles across), though many others are only a few thousand acres.  Here is a website to help you find a NWR.  Entrance to most NWR’s is free or if required, the fee is small. 

Bureau of Land Management land  The BLM oversees more public land than any other US Government agency, though it is mostly in the western US.  There are detailed maps by type of designation here.  Although there can be oil and gas wells, grazing, mining and other non-nature activities on BLM land there are also many wilderness areas and most BLM land can be walked on without restriction.

Private preserves  Although private preserves are not usually shown on state and national maps, there are a great many preserves across the US that have excellent facilities for watching wildlife or exploring the vegetation.  The Audubon Society has many bird sanctuaries across the country; the 11,000 acre Corkscrew Swamp in Florida has the longest nature boardwalk in the US.  From it, many species of epiphytic bromeliads and orchids are visible, as well as birds, especially in the late dry season.

The Nature Conservancy has a similarly large network of preserves, focusing on rare or endangered species.  These preserves tend to be somewhat less accessible to the general public.  And at the very local level, many cities have nature preserves and environmental education facilities with trails and wildlife viewing opportunities.

Key Differences between US Parks and Parks in other parts of the World

In all of the reserves and parks described above there is generally no one except reserve/park staff living on the premises.  In the US there is no equivalent of Rural Parks or National Parks in the European sense – where towns and human settlements are embedded within the park.  Likewise, the private sector tends to play a larger role in European Parks, including staffing of visitor centers, and there is a greater emphasis on selling items in Park stores that are only vaguely related to the park or its natural history.  We have noted a change over the past decade (not really quantifiable) where the European parks are now providing more information to visitors – such a maps and brochures, that we did not see earlier.  In other areas, such as southern Africa, there is still a lack of even basic information provided at the park entrances.  Everything about the parks is purchased at shops in the rest camps.  This is a bit surprising from our perspective, since entrance fees may be $30 or more per day for non-residents.  Certainly a single sheet with basic information could be provided as part of this fee?

All National Parks and many State parks, as part of your entrance fee, give you a brochure with useful information about the park.  These usually highlight key aspects of the history, fauna, flora and geology of the park as well as maps showing the trails.  National parks also produce a small free newsletter, updated seasonally, about the park which you can also get at entrance stations or visitor’s centers.

Parks are just the starting point

Knowing where the parks are is just the beginning of your planning activities.  Here are some strategies we use when planning travel to see natural areas in the US.  We now have a teardrop trailer to sleep in so we look for camping areas, but most visitors from overseas will need regular accommodations.  One option for oversea visitors is the rental of a recreational vehicle (RV) which can be expensive but an option if you have a large group or family and you want to spend time in campgrounds.  RV’s are widely owned in the US, but unless the foreign visitor has experience driving them, we would not recommend them.    They are difficult to manage on narrow roads or dirt roads, when pulling off on the shoulder of the road to look at something, and when parking almost anywhere.

Where to fly in to?

Try a smaller airport.  No, you probably can’t get a direct flight from Heathrow to Tallahassee, Florida.  But you can fly direct to Atlanta and take a connecting flight to Tallahassee (about an hour).  Why do this?  Because small airports are easier to get into and out of – when renting and returning a car, when walking through the terminal and especially, getting out into the countryside (or onto a main highway) with your rental car.  Compare the images below (to same scale).  Large urban airports can be stressful for an arriving foreign tourist in most aspects – baggage, rental car, driving to “escape” the city.  Much smaller secondary airports can be a pleasure to use by comparison, though they require internal connecting flights to international airports like those in Atlanta, Dallas, Chicago, Los Angeles or Seattle.

Getting around

A rental car is a must in the USA for nature exploration.  The mass transport system may be suitable in the large urban areas of eastern cities, but it does not serve the countryside.  Most people fly when needing to travel more than 500 miles – if they live close to an airport.  The nationwide Greyhound Bus line goes to a great many small towns, but is taken only by those who have few other options.  And there is the national passenger rail line Amtrak, but their lines are limited and it is usually more expensive than flying.

There is usually no need for a high clearance 4×4 for most road travel in the US – even to see wildlife.  Most wildlife refugees, national parks, state parks, and even national forests have roads that are accessible to passenger vehicles.  Of course, there are high clearance-only roads in many parks, but these are not essential for seeing much of what the average nature traveler will want to see (at least on a first or second visit).  We have 4×4 vehicles, but rarely need the off-road capability – it is more “peace-of-mind” for when the normally good dirt road gets rough or muddy because of weather.  The one big advantage of a 4×4 high clearance vehicle is that you can somewhat escape the crowds by getting on to rough roads that the RV’s and sedan cars correctly won’t want to take.  If you plan to carry lots of camping gear, a good-sized ice chest, and field guides and camera equipment, you probably need to rent a larger sports utility vehicle.  Most of your driving will be on highways so you will want a larger vehicle capable of comfortable long-distance, freeway-speed driving.

Interstate freeways (labeled like I-40, I-95 etc) criss-cross the US.  These are limited access highways similar to the Autobahn in Germany or Motorways in England.   We take these when we need to cover lots of distance rapidly.  No intersections or traffic circles (relatively rare in the US), just occasional rest stops or offramp to get off for breaks.  The big downside of freeways is that they are loaded with trucks!  You cannot stop on the side of the these highways – they are well-fenced and the traffic is moving too rapidly.  Traffic on most of the US Interstates (in the countryside) is not nearly as heavy as on the European motorways, but it is still undesirable for nature-viewing.  For this reason we design our travel routes to minimize traffic and select roads that allow for periodic pull-offs to look at the landscape.  Tip:  avoid country roads that connect larger cities.  One can use Google Street View to judge the conditions of highways (and most other roads) in the US – the Street View coverage is generally excellent.

Remember that in the US you pump your own gas into your vehicle.  There are almost no “service stations” left – everyone pays via credit card at the gas pump and they pump their own gas.  Gas stations often have clean bathrooms and a convenience shop, some also have ready-to-eat food.

24-hr everything

Unlike much of the world, the US has many 24-hr stores.  Many gas stations, Walmart Supercenters, and certain restaurant chains will be open all the time.  If not, they will close late and open early.  This can be enormously convenient for you when traveling. Naturally, the more remote your location, the less likely this will be true.

Stocking up prior to and during your travels

We would recommend for longer visits (a month or more) that the visitor consider buying (or bringing) basic camping gear and buy an ice chest and miscellaneous cooking gear.  While there are many excellent stores selling such items of all quality levels, there is always a Walmart store relatively nearby (according to the Walmart website 90% of the US population lives within 10 miles of a Walmart or Sam’s Club store).  If you are not familiar with Walmart Supercenters you will be by the end of your trip.  It is the dominant large shopping store in the USA.  To see its growth since 1960 see this animation (up to 2010).  Some Walmart stores are older and relatively small, but the “Supercenters” should be large enough for most visitor’s needs.  The prices are usually lower than other stores (a problem affecting local merchants across the US).  So if the foreign visitor has forgotten to bring something from home, an equivalent can usually be found at Walmart.  Supercenters also have groceries so one stop can probably take care of most of your needs.

Buy a National Park Pass

Entrance fees to US National Parks are inexpensive compared with commercial attractions, especially considering they are valid for a week and this covers all people in the vehicle.    If you plan to visit multiple parks (or other Federal lands with fees) a better option is to buy an Annual pass.   These passes cover not only National Parks and National Monuments, but National Wildlife Refuges (where they may or may not charge an entrance fee) and many National Recreation areas (within National Forests).  Visiting just three National Parks usually pays for the pass.  

Unlike many parts of the world, foreign tourists pay exactly the same entrance or other fees as US nationals. This is also true for state parks and virtually every other attraction in the US.  

Flora and Fauna information

Field guides, floras, books to help plan your travels.  All these are best bought before you travel so you can use them for planning.  However, our experience has been that many sources of information you will not even be aware of until you arrive in a country.  So we recommend planning a visit to the best bookstore possible early in your trip.  However, bookstores (Barnes and Noble being the largest) are going the way of dinosaurs, and your best sources of nature information might be in the national park stores when you start visiting them.  The books in these stores usually cover parks and nature in the entire region – for example a park in southern Arizona might have nature books for the entire southwestern US.

Visitor Centers

Something that the USA does have over almost any other country is the number and quality of visitor centers in parks and public lands that are available to the tourist.  Entrance to nearly all of these visitor’s centers is free.  These centers are essential resources for the visitor, whether they are coming from another state or another country.  There are almost always park staff ready to answer questions about the park – where are the best trails for seeing something, or what wildlife viewing opportunities are best for the time you might have available.  Often, there are good nature dioramas or other displays.  

At many visitor centers you can also view a free informative movie about the park.   Visitor centers are also good places to find out about free ranger-led walks.  Subjects, duration and times vary depending on the park, but they are often very informative.

Visitor’s Centers usually have an associated store where there are many field guides and other books related to nature of the region.   Of course, there are likely to be miscellaneous souvenirs like T-shirts and coffee mugs with the Park’s name, but the focus is more on educational materials than we have seen in comparable park shops in South Africa or elsewhere.  Stopping at these visitor’s centers is an extremely valuable step in your US travels.

Travel strategies

Two trips of three weeks may be more effective than one trip of six weeks.  Why?  Because you will learn what does and doesn’t work well in the first trip – making your second trip that much more effective.  And the material you obtain during your first trip will help you plan the second.  Yes, the airfare will be twice that of a single trip, but airfare will quickly become a secondary part of your total trip cost after a week in the US.  We urge visitors not to try to minimize every expense – cooking all your own food, sleeping only in campgrounds or Walmart parking lots.  You will spend too much of your time trying to save money and not seeing the landscape.  Plan your travel budget to include hotels, rental cars, and fast food meals at the minimum.  Fortunately, most Government-run facilities (parks, national forests etc) are very low-cost compared with commercial attractions (like Disneyworld or Seaworld) so these expenses should only be a minor part of your travel budget.   Hotels in the countryside are usually less expensive than urban hotels – we avoid staying in larger cities wherever possible.  In fact, we tend to avoid larger cities wherever possible – and if not possible – we tend to go through them on the freeways.

If you are planning to visit popular National Parks, you may want to try to do this during the low-season.  Why not spend the summer in Death Valley National Park (California) where the average July high temperature is 116˚F (46.6˚C) or the Everglades National Park (Florida) when the mosquito density is truly impressive?   You will have the park almost to yourself!  You will also then understand why summer is low season in these areas. Seriously, most foreign tourists come to the US when they are able to take time off, and this is usually the June-September period, or the time around Christmas and New Years.   Winter is less crowded (unless you go to south Florida), but snow can also close or complicate travel to many northern Parks.  Monthly visitation statistics for all National Park Service areas can be found here.

Holidays to avoid

Americans have a handful of major holidays when it is advisable for foreign tourists to avoid – or plan your activities around them.  The beginning and ending of the unofficial “summer” vacation are Memorial Day (last Monday in May and Labor Day (first Monday in September).  These three-day weekends are very crowded in parks – especially those near urban areas.  The 4th of July can fall on any day of the week – if it is near a weekend there will also be large crowds at local parks.  There are other, less important government holidays (Veterans Day in November, Columbus Day in October, President’s Day in February and Martin Luther Kind Day in January but most businesses remain open.

There are two major Holidays that, while very important in the US, are not likely to affect a foreigner’s travel in the US to the same degree as Memorial Day and Labor Day.   They are Thanksgiving (last Thursday in November) and the period from Christmas (Dec 25th) to New Years Day (Jan 1).  Thanksgiving is uniquely American, and is where family members get together for a feast.  The entire week is a heavy travel week – but not to see or stay in parks or nature reserves.  Likewise for the Christmas to New Year’s period.  Many people may be traveling during this time to the Caribbean or a warm destination (south Florida or southern California perhaps), but most of the US is cold and few people will be traveling to see parks at this time.

Weekends and cities

If you can, try to avoid visiting parks on weekends when they will be populated by locals.  This is especially true where parks are near large urban areas.  In places far from urban population centers the weekend crowds will be less.  It is better to visit urban areas during the weekends when commuting traffic is less.

Gas

Gas/Petrol is inexpensive compared with much of the rest of the world (unless you live in the Middle East or Venezuela where it is subsidized).  So driving long distances is mostly a consideration of time and fatigue rather than gas cost.

Food

There are innumerable restaurants in the US, and many foreigners may already be familiar with them as many are now international (KFC, McDonalds, Burger King, Pizza Hut etc.) There are many, many chain restaurants, some are found all across the US while others may be regional (like Sonny’s, a barbecue chain found only in the southeast US).  For predictability and low cost, it is hard to beat the fast food chains.  For slower dining, the other chains or local restaurants may be a better choice.  Since time is valuable on a vacation, our recommendation might be to eat your own breakfast (most motels provide “something”), have a fast lunch, and then when the sun has gone down, have a good meal wherever you want.  Try not to miss the good wildlife watching hours and photography hours (after sunrise and before sunset) – by being stuck in a slow service restaurant.

Whatever a foreigner’s perceptions of American food might be, one thing is that it tends to come fast and you don’t have to wait around to ask the waiter for the bill.  This is different from restaurants in many parts of the world where a meal can be relatively expensive and tends to be a savored experience.  

Time is money

You might not want to have this attitude, but vacation time is expensive.  If you consider airfare, hotel, food, rental car, and other expenses you will realize this.  Foreign travel is a luxury for most of the world.  If you spend say $3000 for a 15-day trip to the US this is $200 per day.  And the time you really have available to “explore” (after subtracting the time spent in sleeping, eating, driving, getting gas for the car, etc) might only be 8 hours a day.  Thus each productive hour is costing you $25!  So if you take an extra hour for lunch – that is like adding a $25 item to your lunch bill!  Terrible to think this way, but business people and many others do.

Accommodations:  Motels or camping?

A few comments are in order about accommodations in the US.  The vast majority of travelers in the US use motels (motor hotels) or hotels.  The term “motel” in the US refers to any lodging where you (usually) park near your room and there are no other real facilities.  Hotels will have a restaurant and other services, and are usually found in cities.  Breakfast is usually included in most motels.  There are chain motels (Motel 6, Comfort Inn, Holiday Inn etc) that are found across the country.  There are also “mom-and-pop” motels, run by individuals.  These are often less expensive, though “standards” vary more widely than with the chains.

Camping is very common in parks, but differs in some ways from camping elsewhere in the world.  For example, there are no communal cooking facilities in US parks like there are in Australia or European-influenced countries.  Campers in the US bring their own stoves, pots and the likes.  Picnic tables are usually present in campsites in most parks.  Campers either use an ice chest or a refrigerator (in their RV or trailer).  Electric plugs are common in many campgrounds, but are not universal, especially in national forest campgrounds.

Campsites in US parks tend to be more separated than those in many southern Africa parks or in Australia but this is not universally true.  Online information is available that shows images of many of the US campgrounds – and even the individual campsites. One such site (unfortunately with ads) is here.

Should you camp during your US travels?  If you plan to spend months in the US and have limited funds available to you – you probably shouldn’t come!  The US isn’t a place where cutting corners and being cheap is encouraged.  But, there are major advantages to camping.  They include 1) cost, which can vary but will always be less than a motel and 2) being closer to nature – you will hear that owl in the night (or your camp neighbors talking).  You will also have a shorter commute to your park.  The downside of camping is that it takes time to prepare meals, to shower (not all campsites have showers) and to put away your tent and camping gear.  This is time potentially taken away from seeing what you want to see.  And you might not get a good night’s sleep if it is too hot or too cold.  And you have to bring your camping gear with you when you fly – or buy it on arrival.  Fortunately, the cost of camping gear is reasonable in the US – probably the equivalent of a few nights in a motel.  So if your trip is long, camping is a potential cost saving measure and can put you close to where you want to be.  For a short trip to a region that might be unpleasant to camp in (southern US in summer) motels might be a better choice.

Connectivity

The foreign visitor should have a smart phone so that internet can be accessed while on the highway.  Most motels/hotels have free internet access, as do many fast food restaurants.  If you are traveling with a laptop computer (to download or examine photos for example) you should have no trouble getting free wi-fi at many locations.

Know the climatology and closure dates for roads and some parks

Winter snows can close many roads and parks, so travel will be best in the warmer months of the year.  However, in the southern US it is hot and humid in summer and travel here during this period requires that you have good reasons or specific items to see.  Likewise for the southwestern desert areas.  Hotel rates are lowest in Phoenix in July, when the daytime temperature averages 45˚C!  However, some nocturnal reptiles (snakes, geckos etc) are easiest to see at this time of year (at night).  Many species of Hummingbirds migrate into southeast Arizona from Mexico during the summer months when “monsoonal” rains stimulate the vegetation growth.  So each season has its features worthy of observation, but the comfort levels can vary a lot between the seasons.  If the area is comfortable for tourists – it is likely high season and expensive!  South Florida is very expensive in the winter months, when much of the eastern US tries to visit there to escape winter cold.  In the summer, the heat and humidity drives tourists away (except from Latin America, who aim for the air-conditioned urban areas).

Our recommendations for where to go and what to see

What we would recommend for the foreign visitor to see?  What is unique?  This of course depends so much on what the visitor’s interest’s are.  Let us take the example of Florida.  Most tourists travel there to escape winter weather, to visit Miami, or to visit Disney World.  All of these are justifiable, depending on where you are coming from.  For the naturalist, we might suggest different attractions.  For example, to see large wading birds you need to travel to southern Florida in the winter/spring time (dry/cool season).  Many tourists can become overwhelmed by the stream of advertising from commercial attractions in south Florida and miss the most iconic locations.  Go straight to the Everglades National Park (not commercial attractions on its fringes) for the best winter wildlife viewing.   There are two quite separate locations worth your while – the Anhinga Trail near the Park’s main visitor center and Shark Valley (a misnomer because the place is nearly flat) on the north side of the park. In the winter time you can see many wading and water birds (Ibises, Anhingas, Herons etc.) as well as turtles and alligators that often bask next to the trails.  

In central Florida, close to the popular Disney World annually visited by millions of tourists, there is an area in the Ocala National Forest that offers spectacular springs with cool (68-74˚F) crystal-clear water ideal for snorkeling.  At some of the springs the visitor can also rent canoes or camp.  A small fee is charged to day visitors to swim or picnic.  These are mostly used by locals.   Because the water temperature is constant year-round you can snorkel in these springs in mid-winter and have the springs almost to yourself!

In northern Florida we head to the Apalachicola National Forest to explore for carnivorous plants and any reptiles and amphibians we might see on the lightly-traveled forest roads.  Tourists (whether national or international) rarely come here – unless they are botanically-inclined and have read material before coming.  

In summary, our perceptions of what is unique in Florida differs from most tourists to the state.  While many people know about the Everglades (though not the interesting details like the diversity of palms, bromeliads and orchids found there), very few tourists know about the springs in central Florida and their fauna, and even fewer tourists know about exploring the National Forest lands in the “Big Bend” region of north Florida.

Unfortunately, we do not have the time or background to exhaustively cover all of the US locations of high interest for nature-oriented travelers.  Some general guidance can be found in biodiversity material available online and presented in the next section.

General Biodiversity of the US

The “ecoregions” of the US have been classified in various manners.  The Environmental Protection Agency (EPA) uses one type of classification while the World Wildlife Fund uses another, more vegetation-specific classification.  An excellent interactive means of visualizing the USA’s natural ecoregions is this site.

For a “quantitative” look at the biodiversity of the USA one can look at interesting maps produced by Clinton Jenkins.  I have selected a few below, but there are many more at his website.  These maps of biodiversity are useful for determining what you might see in a day’s traveling around your location – all of the diversity won’t be found on the same hillside.  But it will be found within perhaps 50 km (30 mi) of your location.  Of course, this is the maximum diversity, and you will only see a fraction of it.  But the maps suggest which parts of the US are better for looking for the diversity.

A lengthy discussion of the flora of the US and its geographical distribution is  found on the website of BONAP.  Among the many informative maps are ones of regional plant endemism,  and a map showing the vascular plant species richness (number of species per 100 by 100 km area).  There are many other maps, including ones showing carnivorous plant diversity (greatest in the SE US), shrub diversity (greatest in southern California), and many plant types (e.g. annuals – greatest in California) or families (e.g. cacti).

While the eastern deciduous forests have a greater number of species of some birds and amphibians, the West has more spectacular scenery and more apparent lizards and snakes.  And the desert environments in the southwest are decidedly different from what many European tourists will have experienced at home.  The cacti-covered landscapes are particularly interesting from a botanical perspective.  Big Bend National Park in southwest Texas has more cacti species (about 60) than any other part of the US, though many of these are small and inconspicuous (but fun to look for!).  

Southern Arizona is the land of conspicuous cacti and other succulents like Agaves and Yucca.

California, tempered by the Pacific Ocean to its west, has the greatest biodiversity of any state due to the extreme topographic and climatological variations.  To wander in the Coast Redwood groves (especially the Founders Grove in Humboldt Redwoods State Park) is an experience unlike that of any other forest on Earth.  And on the slopes of the Sierra Nevada (inland from where the Coast Redwoods are found) are the Giant Sequoia – slightly shorter trees but more massive.  The best groves are in Sequoia National Park.  Of course, these are “mega-botanical” features, but there are a great many other interesting plants and environments in California that are far-less touristy.  

Naturally, nature tourism is much more than ticking off one species after another – of whatever kind.  It is important to take the time to understand and appreciate the variety of unique environments/ecosystems, and simply appreciating unspoiled landscapes has its own special value.  The glaciers streaming down Mt Rainier, hiking in the high Sierra Nevada, seeing the Grand Canyon from almost any vantage point, or canoeing in bald cypress swamps of the southeastern US are all unique and valuable experiences.  

In summary, we really can’t provide an unbiased perspective on where the foreign visitor should go to see “nature”.  There are too many places worth visiting in the USA, though our favorites are generally in the southern part of the country.  Effective nature tourism depends mostly on being prepared for the unexpected, and knowing as much as possible about what you are interested in seeing.  Sometimes unplanned visits to natural areas prove to be the most rewarding.