Why go
A Boston–Washington journey raises different transport questions from a trip across the western states. Understanding that contrast helps you compare a rail corridor with long road or air journeys. The Interstate system, intercity buses and Amtrak serve different kinds of travel rather than forming interchangeable national networks.
The full story
The United States developed extensive road connections through U.S. Highways and the Interstate system. These roads support travel within states as well as journeys between them. Intercity buses form another part of that road network, distinct from driving a private vehicle. Railways have a different role for freight and passengers. Long-distance freight remains an important use of the railway network, while passenger travel is less central to national transport. Amtrak carries intercity passengers, with the Boston–Washington corridor a notable contrast to the much longer journeys between distant urban regions. Rail also has a role around Chicago and in parts of California. Air travel connects widely separated cities through hubs such as Atlanta, Chicago, Dallas–Fort Worth, Denver and Los Angeles. For planning, the useful distinction is between a connected urban corridor and a journey spanning large distances. Compare the actual connections for your chosen cities before treating one transport mode as the default across the country.