By Plane – Non-stop international flights may enter a variety of cities, depending on the origin, including New York (2 of 3 airports); Boston; Denver; Chicago; Miami; Dallas; Charlotte, N.C.; Seattle; San Francisco and Los Angeles. However, with transfers, you can get to any variety of cities in any state.
By Train – Rail travel is not as well-developed in the United States as in some countries. The East Coast corridors are the most convenient, and certain routes along the West Coast, as well as some cross-country lines. However, only the Acela Express in the Northeast is high speed. Sometimes buses run by the rail company connect some areas. Go to the Amtrak website here and be sure to look for regular specials (“deals”).
By Bus – Bus travel used to be the way to go in the United States, but these days can be very time-consuming, with many stops and transfers. Greyhound is the leading provider. Alternatives Megabus, founded in the United Kingdom, and FlixBus, established in Germany, are two options that can offer great prices and good connections IF you are going to the places they serve (primarily in higher population areas in the west, south and east).
By Car – For better or for worse, the best way to see the United States, other than large cities, is by car, partly because the distances are so large. You can rent a car starting at age 21, but anyone under 25 will pay an additional fee. Plus, you may need to acquire your own insurance and get an an International Driving Permit in your home country since some states require it (as well as a license in your home country). Driving in the United States is on the right side, and you can turn right on red only in SOME states! Speed limits are generally posted but do also vary slightly by state; however, in general, urban areas are 30 mph, four-lane roads are 65, and interstate highways are 70. If you are stopped, stay in the car and await instructions. Do not reach for anything without being asked.