As I was walking ,

That ribbon of highway, I saw above me

that endless skyway, I saw below me,

that golden valley...
                   -Woody Guthrie, c. 1940

The above is an excerpt of a fairly well known folksong about America and it give a fairly accurate illustration of what the country looks like, even many years after Guthrie wrote the song:  redwood forests describe places not far from  San Francisco and Seattle,  diamond deserts still dominate the Southwest alongside bull riders, and although the highways Woody Guthrie knew were replaced by the Interstate System about 15 years later, roads of all kinds still ribbon along under big blue skies that seem to go on forever, especially on the lonelier stretches where fewer people live.  

Flowery words aside, the United States is an attractive option to spend time outdoors in.  Going down to the old swimming hole in Georgia is as  time honored  a tradition as  taking the little ones into the canyons to see ancient pictographs in Arizona.

Overview (or, "Wow, this place is huge!")

Visitors often underestimate exactly how large the United States actually is in terms of the territory it occupies: the lower forty-eight states at least don't look quite so large on a world map. The truth actually  borders on the staggering: for example,  the distance between the most populous West Coast city (Los Angeles)  and the most populous East Coast city (New York City) is 2,444 miles (3,933 km.) That is  900 miles longer than the distance between London and Moscow. The distance between Chicago and Miami is about 200 miles shy of the distance between Sydney, Australia and Wellington, New Zealand, and Texas is about as large as the entire nation of France.  It is not a problem for locals to see what scientists qualify as an entirely different biome let alone a different state and this translates into a large variety of places to enjoy for vacation, especially outdoors. A large amount of land is either set aside in national or state parks or as public land which humans simply do not inhabit.

 National Parks

The National Park System was founded under the aegis of Woodrow Wilson's administration almost a  hundred years ago and since his lifetime has expanded to include no less than sixty-two places of natural beauty, the most recent of them set up in 2004.  Each park is part of federally protected land and by extension is federally preserved land that cannot be sold into private hands for development (it takes an act of Congress to set it aside in the first place)  and more often than not these parklands are used for recreation, education, and scientific research: studies of the behavior of wolves and grizzly bears in Yellowstone National Park over the past thirty years have helped inform the decisions of politicians and scientists grappling with the reappearance or reintroduction of native fauna in Europe.

Entrance into any park typically costs a few dollars (most of this goes to pay the salaries of the good people who maintain it)  and upon entry one may request a map from any of the front gates or from a ranger station. The map shall include the locations of the "bare necessities"-where all the major hiking trails are,  where to seek out information if one has questions,  where bodies of water are, and yes, in some parks, where one might find the toilet.  These maps are often printed in multiple languages, everything from Chinese to French to Greek,  and if one is not a native English speaker it is a very simple matter of asking. In recent years, many National Parks, especially more popular ones, have set up wireless internet access: this is a boon to visitors because the website of the park one is visiting often contains a large amount of information, including  advisories on weather and trail conditions, podcasts to download,  or  when  and where the  "Ranger Talks" are (these are lectures aimed at either children or adults explaining local wildlife and fauna.)    Bringing a computer, thus, is an excellent idea; just bring a very sturdy, waterproof case to carry it in and keep an extra battery.

National Forests

These are areas with similar protections to National Parks and have similar opportunities for recreation:  some of them, like Kaibab and George Washington, abut National Parks (Grand Canyon and Shenandoah, respectively) as they are a natural transition of habitiat types.  These areas are often overlooked by foreign visitors in favor of the better known National Parks, but doing so is often a mistake: for example, Monongahela National Forest is a large preserve found in the mountains of West Virginia.  It is the home of  nearly as many animal species as Great Smokey  to the South, portions of the Appalachian Trail snake through it with challenging craggy rocks to scramble up and down, and most of all it is the home of the New River Gorge: this is a beautiful place where the mountains drop into a very deep valley cut through by a river with class IV rapids.   (And yes, whitewater rafting is possible.)

National forests are often prime places for backcountry camping (meaning usually camping in areas that are off trail/in remote areas.) If you plan on this, also plan on purchasing  a permit to do this well before you go on the trip as it is required of you and read up on what the individual place you are visiting requires (generally proper disposal of waste is required knowledge, for example.)  In the backcountry it also pays to have a cell phone or (even better) a walkie talkie in case of injury or danger: it could be miles to the nearest ranger station let alone the nearest hospital so tuning into the frequency of the ranger station is a good safety precaution because it will make you easier to locate and evacuate if the situation is severe enough.