The size of the US and the distance separating major cities make air the dominant mode of travel for short term travelers. But if you have time, travel by car can be interesting.

By plane

By far the most convenient form of intercity travel in the USA is air travel. Coast-to-coast travel takes about 6 hours, compared to the days or weeks necessary for land transportation. Most cities in the US are served by one or even two airports, with many small towns also having some passenger air service. A hub and spoke system of air travel is most common. In this scheme small cities' air traffic go first to a hub city where traffic is aggregated before flying on to the destination city. Transfer for bags checked at the original airport is handled automatically to your final destination. Depending on where you are starting from, it can sometimes be cheaper to drive to a nearby large city and fly from there or, conversely, to fly to a large city near your destination and drive from there. Major carriers compete vigorously for business on major routes, and bargains can be had for travelers willing to book two or more weeks in advance. The converse of this is that most smaller destinations are served by only one or two regional carriers, and prices there can be surprisingly expensive. There are some discount air carriers in the USA and they are becoming more dominant all the time. Southwest Airlines is the largest and best known; unlike its European counterparts, there are significant penalties for not booking in advance.

Online travel agencies, such as Expedia Travelocity and Orbitz list most flights of all the airlines and you can pick and choose based on price, travel time, number of stops, etc. A little time spent familiarizing oneself with these websites can often save considerable money.

There are a number of ways to save money when flying domestically in the United States. See Cheap airline travel in North America.

By train

Passenger trains in the United States are surprisingly scarce and relatively expensive. Service is severely under funded with respect to the other major forms of travel (highways, air), and therefore, quite limited. Passenger rail in the USA is now nationalized since private carriers dropped passenger service and focused on more lucrative freight transport, although intraregional commuter passenger travel is alive and well, carrying workers from the suburbs into some of the larger cities, including Chicago and New York City, among others. The national rail system, Amtrak (1-800-USA-RAIL), provides service to many cities, concentrating more on sightseeing tours than efficient intercity travel. They have promotional discounts of 15% for students and seniors, and a 30-day USA Rail Pass for international travelers only.

A major Amtrak line in regular daily use by Americans themselves is the Northeast Corridor line, running between Boston and Washington (D.C.). It stops in New York, Philadelphia and many other cities on the way. This line is electrical, with top speeds of 150 miles per hour (though the average speed is a good deal slower). The fastest trains are the Metroliner and the Acela Express, both of which have first class service, but can be quite expensive. Given the difficulty and expense of getting from the center of some of the major Northeastern cities to their respective airports, trains can sometimes be more convenient than air travel. While some trains in the Northeast Corridor and other medium-distance lines do not require advance reservations, the premium trains and most of the long-distance trains do require such reservations. During usual American vacation times, some long-distance trains can sell out weeks or even months in advance, so it pays to book early if you plan on using the long-distance trains.

One major scenic long-distance train route, the California Zephyr, runs from Emeryville in the Bay Area of California to Chicago, via Reno, Salt Lake City and Denver. The full trip takes around 60 hours, but has incredible views of the Western deserts, the Rocky Mountains, and the Great Plains, things that you just cannot see if you fly. Many of the sights on this route are simply inaccessible to cars. The trains run only once per day, and they usually sell out well in advance. Amtrak also provides reasonably speedy daily roundtrips between Seattle and Vancouver, Canada and several daily trips between Seattle and Eugene, Oregon on the Amtrak Cascades line.

By car

America's love affair with the automobile is legendary, and most Americans prefer the convenience of car travel for getting to nearby cities in their state or region. Many "snowbirds" drive to a haven in the south for the winter so that they have their auto with them. Besides intercity travel, a car can be necessary even to get around in a single city. Travelers from outside the country may not sufficiently appreciate the need for an automobile in the USA. Of course in very large cities like New York City or Chicago there are extensive in-city bus service and large numbers of cruising taxicabs, but in most medium-sized American cities, particularly in the west and south, cities are very spread out and bus service thin. Taxis are always available but you may have to call ahead for one and wait a half-hour or so to be picked up, and then you have the problem of getting back and you will probably have to call again and wait. Even in very large cities, like Los Angeles, getting around by taxi is a very unreliable for travel, although buses run throughout the city.

A romantic appeal is attached to the idea of long-distance car travel; many Americans will tell you that you can't see the "real" America except by car. Given the dearth of public transportation within American cities, the loss of time traveling by car between cities, compared to flying, can be made up by the convenience of driving around within cities once you arrive. In addition, many of the country's major natural attractions, such as the Grand Canyon, are almost impossible to get to without an automobile. The United States is covered with a convenient system of interstate highways, funded by the federal government, and built and maintained by the states. These huge roads stretch from one end of the country to the other, either north-south or east-west, and can make it easy to eat up long distances in record time.

Renting a car in the USA usually runs anywhere from $30 and $100 per day, with some discounts for week-long rentals. The major rental agencies are Hertz (+1 800 230 4898) and Avis (+1 800 230 4898). There are no large national discount car rental agencies but in each city there is usually at least one. The internet or the Yellow Pages are the easiest ways to find them. One more or less national chain is Rent-A-Wreck (+1 800 944 7501). It rents used cars at significantly lower prices. Most rental agencies have downtown offices in major cities as well as offices at major airports. Not all companies allow picking up a car in one city and dropping it off in another, and most have higher rates for long-distance travel; check with the rental agency when making your reservations.

Most rental agencies accept an International Driver's Permit only when presented along with a valid Driver's license from your country. You may wish to join some kind of auto club before starting a large American road trip, and having a cell phone is a very good idea. Most rental agencies have some kind of emergency road service program, but they can have spotty coverage for remote regions. The largest and most popular club in the United States is The American Automobile Association (1-800-391-4AAA), known as "Triple A". A yearly membership runs about $60, which is well worth the peace of mind. AAA members also get discounts at many hotels, motels, restaurants and attractions; which may make it worth getting a membership even if you don't drive. Alternatively, Better World Club (1-866-238-1137) offers similar rates and benefits as AAA with often timelier service and is a more eco-friendly choice (1% of revenue is donated to environmental cleanup programs). Traffic signs with too many English words in the USA can be very unfriendly and even dangerous to foreign drivers who cannot read English, such as signs with words only saying "NO TURNS", "NO MOTOR VEHICLES", or "NO PARKING". The USA is very slow adopting signs with symbols. Foreign drivers who cannot read English may better avoid driving themselves.

Unlike most other countries and areas in the world, almost every traffic sign uses non-metric units like the inch (25.4 mm), the foot (0.3048 m), the mile (about 1.609 km), the pound (about 453.59 g) and the short ton (about 907.18 kg) even though metric traffic signs are now federally legal per Manual on Uniform Traffic Control Devices unless a state law says otherwise. When units are not specified, speed limits are posted in miles per hour and distances are posted in miles. Gasoline is sold by the gallon. The American gallon is smaller than the UK gallon, and one American gallon equals 3.785 liters. Also, octane is lower than in Europe. Gas prices have been on the rise since the start of the century, and have hit a national high of US$2.55 per gallon in mid-summer of 2005, but since then gas prices has sharply dropped. The national average as of December 2005 is 2.17 per gallon, with the cheapest places being in the Midwest and southeast, but places like Honolulu and San Francisco can still level off about 2.50-2.60 a gallon.

By bus

Intercity bus travel in the United States is widespread, but is not available everywhere. Many patrons often use bus travel when other modes aren't readily available, as buses often connect many smaller towns with regional cities. Many of the disadvantaged and elderly often use these bus lines, as automobile travel proves arduous or unaffordable for some. Greyhound Bus Lines (+1 800 229 9424) has the predominant share of American bus travel. Their North American Discovery Pass allows unlimited travel for ranges of 4 to 60 days, but you might want to try riding one or two buses first before locking yourself in to an exclusively-bus American journey. For bus service between large East Coast cities (particularly Washington, D.C., New York City, Philadelphia, and Boston), travelers can purchase deeply discounted (below Greyhound prices) tickets from a number of small operators, typically called "Chinatown bus" operators, because they usually enter and depart from the Chinatown area of the cities they serve.

By thumb

A long history of hitchhiking comes out of the U.S., with record of automobile hitchhikers as early as 1911. Today, hitchhiking is not as common, but many thousands of people still take short or cross-country trips each year. The laws related to hitchhiking in the U.S. were most recently proposed by the Uniform Vehicle Code (UVC) and adopted with changes in wording by individual states. In general, it is legal to hitchhike throughout the majority of the country, if not standing within the boundaries of a highway (usually marked by a solid white line at the shoulder of the road) or if not on a major interstate highway prohibiting pedestrians. In many states interstate highways do not allow foot traffic, so hitchhikers must use the entrance ramps. In a few states it is allowed or tolerated (unless on a toll road). Oklahoma, Texas and Oregon are a few states that do allow pedestrians (i.e., hitchhikers) on the highway shoulder, although not in some metropolitan areas. Oklahoma allows foot traffic on all free interstates, but not toll roads) and Texas only bans it on toll roads - and on free interstates within the city of El Paso. Oregon only bans it in the three counties that make up the tri-met transit district (Multnomah, Clackamas and Washington (Metro Portland).) Missouri only bans it within Kansas City and St Louis city limits. If traveling smaller highways, make sure to stay on the far edge of the shoulder and walk facing traffic. Holding a sign with your destination or raising a thumb both work, as most Americans understand that you are requesting a ride.