section_path: Economy/Transportation
section_name: Transportation
paragraph_text: Transportation
  
  The overwhelming majority of roads in the United States are owned and maintained by state and local governments. Roads maintained only by the U.S. federal government are generally found on federal lands (such as national parks) or at federal facilities (like military bases). The Interstate Highway System, with its large, open freeways linking the states, is partly funded by the federal government but owned and maintained by the state government hosting its section of the interstate. Some states fund and build their own large expressways — often called " parkways " or " turnpikes " — that generally use tolls to pay for construction and maintenance. Likewise, some privately owned roads may use tolls for this purpose.
  
  Passenger and freight rail systems, bus systems, water ferries, and dams may be under either public or private ownership and operation. U.S. civilian airlines are all privately owned. Most U.S. airports are owned and operated by local government authorities, and there are also some private airports. The Transportation Security Administration has provided security at most major airports since 2001.
  
  The U.S. Department of Transportation and its divisions provide regulation, supervision, and funding for all aspects of transportation except for customs, immigration, and security. (The latter remain the responsibility of the U.S. Department of Homeland Security.) Each U.S. state has its own department of transportation, which builds and maintains state highways. Depending upon the state, this department might also directly operate or supervise other modes of transportation.
  
  Aviation law is almost entirely the jurisdiction of the U.S. federal government. Vehicle traffic laws, however, are enacted and enforced by state and local authorities, with the exception of roads located on federal property (national parks, military bases) or in the unorganized U.S. territories. The United States Coast Guard is the primary enforcer of law and security on U.S. waterways, inland as well as coastal, but economic jurisdiction over coastal tidelands is shared between state and federal governments. The country's inland waterways are the world's fifth-longest, totaling 41,009 km (25,482 mi).
  
  Of the world's 50 busiest container ports, four are located in the United States. The busiest in the U.S. is the Port of Los Angeles.
  
  Personal transportation in the United States is dominated by automobiles, which operate on a network of 4 million miles (6.4 million kilometers) of public roads, making it the longest in the world. The country's rail transport network, also the longest in the world at 182,412.3 mi (293,564.2 km), handles mostly freight.
  
  Privately owned railroads and trains were the dominant mode of transportation in the U.S. until the mid-twentieth century. The introduction of jet airplanes and airports serving the same major city routes accelerated a decline in demand for intercity rail passenger service by the 1960s. The completion of the Interstate Highway System also hastened the sharp curtailment of passenger service by the railroads. These significant developments led to the creation of the National Railroad Passenger Corporation, now called Amtrak, by the U.S. federal government in 1971. Amtrak helps to maintain limited intercity rail passenger service in most parts of the country. It serves most major U.S. cities, but outside the Northeast, California, and Illinois it typically runs only a few trains per day. More frequent Amtrak service is available in regional corridors between certain major cities, particularly the Northeast Corridor between Washington, D.C., Philadelphia, New York City and Boston; between New York City and Albany; in metropolitan Chicago; and in parts of California and the Pacific Northwest. Amtrak does not serve several major U.S. destinations, including Las Vegas and Phoenix, Arizona.
  
  The Oldsmobile Curved Dash and the Ford Model T, both American cars, are considered the first mass-produced and mass-affordable cars, respectively. As of 2023, the United States is the second-largest manufacturer of motor vehicles and is home to Tesla, the world's most valuable car company. American automotive company General Motors held the title of the world's best-selling automaker from 1931 to 2008. The American automotive industry is the world's second-largest automobile market by sales, having been overtaken by China in 2010, and the U.S. has the highest vehicle ownership per capita in the world, with 910 vehicles per 1000 people. By value, the U.S. was the world's largest importer and third-largest exporter of cars in 2022.
  
  The American civil airline industry is entirely privately owned and has been largely deregulated since 1978, while most major airports are publicly owned. The three largest airlines in the world by passengers carried are U.S.-based; American Airlines is number one after its 2013 acquisition by US Airways. Of the world's 50 busiest passenger airports, 16 are in the United States, including the top five and the busiest, Hartsfield–Jackson Atlanta International Airport. As of 2022, there are 19,969 airports in the U.S., of which 5,193 are designated as "public use", including for general aviation and other activities.