Public transportation in the U.S. refers to publicly funded public transportation services. This includes a variety of bus, rail, ferry, and sometimes airline services. Most established public transportation systems are located in central urban areas where population density and public demand are sufficient to make use of public transportation. In more auto-centric suburban areas, public transportation is usually, but not always, less frequent and less frequent. Most public transportation services in the United States are national, regional/suburban, or local, depending on the type of service. Also, sometimes “public transportation” in the United States is a generic term synonymous with “alternative transportation,” meaning any form of mobility that excludes driving alone in a car.

Most rail transportation in the United States is publicly funded at all levels of government. The national Amtrak rail system provides service throughout the contiguous United States. The frequency of Amtrak service varies depending on the size of the city and its location along major rail routes. For example, cities such as New York City and Washington, D.C., which are located along the busy Northeast Corridor, can receive up to 50 Amtrak trains a day. from their stations. The same corridor is home to the only operating high-speed rail network in the Americas : the Acela Express. Other smaller cities, such as Dodge City, Kansas, for example, may have only two trains a day, or, in rarer cases, cities in the upper Midwestern states, where there is little population, may have Amtrak service only two or three times a week. Regional rail service is mostly assigned to a major city or state. For example, Long Island Rail Road serves the Long Island suburbs of New York City, and the UTA FrontRunner serves regional rail service for the Wasatch Front in Utah. These trains typically run throughout the day, from every 20 minutes during peak hours to 30-45 minutes during off-peak hours. Other rail service that is regional in nature may run only during rush hour.

Currently, there is only one commercial private rail service in the United States, that of Virgin Trains USA (formerly known as Brightline). This service provides regular rail service from Fort Lauderdale to Miami with the long-term goal of connecting Miami with Orlando and becoming the state rail service for the state of Florida.

There are three common types of bus service in the United States: regular bus systems, bus rapid transit (BRT), and intercity buses. Virtually every major city in the United States offers some form of bus service, with some operating 24 hours a day. These buses run on flexible routes and stop frequently, focusing on accessible services for all segments of the population. Bus Rapid Transit attempts to mimic the speed of light rail. Most BRT systems in the U.S. are located in mid-sized cities or satellite towns and serve as auxiliary routes for rail service. The main difference between BRT in the United States and regular bus service is that BRT often runs more frequently because it has fewer stops to speed up service. In addition, BRT service usually has its own dedicated right of way and signal priority, which allows BRT vehicles to move faster than regular automobile traffic.

Several coastal cities offer ferry service linking communities across large bodies of water where building road and rail bridges is not financially feasible. The ferry connection is sometimes pedestrian only, but can sometimes offer platforms for cars and public transportation, depending on the ship used.

Long-distance public transportation, which may be too far to travel by train or bus, i.e., cross-country travel or travel into the United States) is more often by air. Most airports in large regions are located on the periphery of major cities and are government-owned, while the aviation services themselves are usually owned by commercial corporations. In some cases, larger airports may use their own rail, bus, and monorail systems connecting the various terminals together.