The vast majority of passenger travel in the United States occurs by automobile for shorter distances and airplane or railroad for longer distances. Most cargo in the U.S. is transported by, in descending order, railroad, truck, pipeline, or boat; air shipping is typically used only for perishables and premium express shipments. Transportation is the largest source of greenhouse gas emissions in the United States.
Ownership and jurisdiction.
The overwhelming majority of roads in the United States are owned and maintained by state and local governments. Federally maintained roads are generally found only on federal lands (such as national parks) and at federal facilities (like military bases). The Interstate Highway System is partly funded by the federal government but owned and maintained by individual state governments. There are a few private highways in the United States, which use tolls to pay for construction and maintenance. There are many local private roads, generally serving remote or insular residences.
Passenger and freight rail systems, bus systems, water ferries, and dams may be under either public or private ownership and operation. Civilian airlines are all privately owned. Most airports are owned and operated by local government authorities, but 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, which are the responsibility of the U.S. Department of Homeland Security. Each state has its own Department of Transportation, which builds and maintains state highways, and depending upon the state, may either directly operate or supervise other modes of transportation.
Aviation law is almost entirely the jurisdiction of the U.S. federal government, and automobile traffic laws are enacted and enforced by state and local authorities except on highways or roads on federal property or in unorganized territories. Economic jurisdiction over tidelands is shared between the state and federal governments, while the United States Coast Guard is the primary enforcer of law and security on U.S. waterways.
Mode share.
Passenger.
Passenger transportation is dominated by a network of over 3.9 million miles of highways which is pervasive and highly developed by global standards. Passenger transportation is dominated by passenger vehicles (including cars, trucks, vans, and motorcycles), which account for 86% of passenger-miles traveled. The remaining 14% was handled by planes, trains, and buses. Public transit use is highly concentrated in large older cities, with only six above 25% and only New York City above 50% of trips on transit. Airlines carry almost all non-commuter intercity traffic, except the Northeast Corridor where Amtrak carries more than all airlines combined.
The world's second largest automobile market, the United States has the highest rate of per-capita vehicle ownership in the world, with 865 vehicles per 1,000 Americans.
Bicycle usage is minimal with the American Community Survey reporting that bicycle commuting had a 0.61% mode share in 2012 (representing 856,000 American workers nationwide).
Cargo.
Freight transportation is carried by a variety of networks. The largest percentage of US freight is carried by trucks (60%), followed by pipelines (18%), rail (10%), ship (8%), and air (0.01%). Other modes of transportation, such as parcels and intermodal freight accounted for about 3% of the remainder. Air freight is commonly used only for perishables and premium express shipments. The difference in percentage of rail's share by ton-miles and by weight (10% vs 38%) is accounted for by the extreme efficiency of trains. A single railroad locomotive may pull fifty boxcars full of freight while a truck only pulls one. Trucks surpass trains in the weight category due their greater numbers, while trains surpass trucks in the ton-miles category due to the vast distances they travel carrying large amounts of freight.
Usually cargo, apart from petroleum and other bulk commodities, is imported in containers through seaports, then distributed by road and rail. The quasi-governmental United States Postal Service has a monopoly on letter delivery (except for express services) but several large private companies such as FedEx and UPS compete in the package and cargo delivery market.
Safety.
The U.S. government's National Center for Health Statistics reported 33,736 motor vehicle traffic deaths in 2014. This exceeded the number of firearm deaths, which was 33,599 in 2014.
In 2020 there was % more road fatalities in the US than in the European Union, or % less in the EU than in the US, with nearly 38,680 in the US, and nearly 18,800 in the EU.
History.
18th century.
In the late 18th century, overland transportation was by horse, while water and river transportation was primarily by sailing vessel. The United States population was centered on its Atlantic coast, with all major population centers located on a natural harbor or navigable waterway. Low population density between these centers resulted in a heavy reliance on coastwise and riverboat shipping. 
The first government expenditures on highway transportation were funded to speed the delivery of overland mail, such as the Boston Post Road between New York City and Boston. Due to the distances between these population centers and the cost to maintain the roads, many highways in the late 18th century and early 19th century were private turnpikes. 
Other highways were mainly unimproved and impassable by wagon at least some of the year. Economic expansion in the late 18th century to early 19th century spurred the building of canals to speed goods to market. One such prominent example was the Erie Canal.
19th century.
Numerous modes of transportation fought for supremacy throughout the Industrial revolution of the 19th century. Canals swiftly took the role of turnpikes, stagecoaches, and wagon routes, which in turn were shortly replaced by steam-powered riverboats. During this period, the advancement in transportation inspired many artists to display the grand contrast from the past to the new. Taking a look at Samuel Colman's work, one piece in particular, "Storm King on the Hudson" (1866) displayed both the older sailboats and the grand steamboats that were overtaking the Hudson River.
Access to water transportation shaped the geography of early settlements and boundaries. For example, the Erie Canal escalated the boundary dispute called the Toledo War between Ohio and Michigan in the 1830s. The disputed Erie Triangle was awarded to Pennsylvania, giving that state access to Lake Erie. Most of West Florida was given to Mississippi and Alabama to guarantee their access to the Gulf of Mexico.
Development of the mid-western and southern states drained by the Mississippi River system (Mississippi, Ohio and Missouri Rivers) was accelerated by the introduction of steamboats on these rivers in the early 19th Century. These three rivers (among others) also form the borders of several states. Prior to the introduction of steamboats, transit upstream was impractical because of strong currents on parts of these waterways. Steamboats provided both passenger and freight transportation until the development of railroads later in the 19th Century gradually reduced their presence.
The rapid expansion of railroads brought the canal boom to a sudden end, providing a quick, scheduled and year-round mode of transportation that quickly spread to interconnect the states by the mid-19th century. During the industrialization of the United States after the Civil War, railroads, led by the transcontinental rail system in the 1860s, expanded quickly across the United States to serve industries and the growing cities. During the late 19th century, railroads often had built redundant routes to a competitor's road or built through sparsely populated regions that generated little traffic. These marginal rail routes survived the pricing pressures of competition, or the lack of revenue generated by low traffic, as long as railroads provided the only efficient economical way to move goods and people across the United States. In addition to the intercity passenger network running on Class I and II railroads, a large network of interurban (trolley or "street running") rail lines extended out from the cities and interchanged passenger and freight traffic with the railroads and also provided competition.
20th century.
The advent of the automobile signaled the end of railroads as the predominant transportation for people and began a new era of mobility in the United States. The early 20th century Lincoln Highway and other auto trails gave way in the 1920s to an early national highway system making the automobile the primary mode of travel for most Americans. Interurban rail service declined, followed by trolley cars due in part to the advent of motorized buses and the lack of dedicated rights-of-way but also by deliberate efforts to dismantle urban rail infrastructure.
The scarcity of industrial materials during World War II slowed the growth of automobile manufacturing briefly and contributed to the nation's declining rail network. In the 1950s, however, the United States renewed building a network of high-capacity, high-speed highways to link its vast territory. The most important element is the Interstate Highway system, first commissioned in the 1950s by President Dwight D. Eisenhower and modeled partly after the Italian autostrada and the German Autobahn system.
By 1945, after the end of World War II, nearly every city in America had at least one electric tram company providing intra-city transportation. There were an estimated 36,377 light rail vehicles in operation. Increased automobile ownership cut this number by 1/3 by 1965.
The airline industry began to successfully compete with intercity rail as a result of government investment, which suffered a loss of ridership. As the civil air transportation network of airports and other infrastructure expanded, air travel became more accessible to the general population. Technological advances ushered in the jet age, which increased airline capacity, while decreasing travel times and the cost of flights. The costs of flying rapidly decreased intercity rail ridership by the late 1960s to a point where railroads could no longer profitably operate networks of passenger trains. By the early 1970s almost all passenger rail operation and ownership had been transferred to various federal, municipal and state agencies.
Freight railroads continued to decline as motor freight captured a significant portion of the less-than-carload business. This loss of business, when combined with the highly regulated operating environment and constrained pricing power, forced many railroads into receivership and the nationalization of several critical eastern carriers into the Consolidated Rail Corporation (Conrail). Deregulation of the railroads by the Staggers Act in 1980 created a regulatory environment more favorable to the economics of the railroad industry.
In the 1990s, the increase in foreign trade and intermodal container shipping led to a revival of the freight railroads, which have effectively consolidated into two eastern and two western private transportation networks: Union Pacific and BNSF in the west, and CSX and Norfolk Southern in the east. Canadian National Railway took over the Illinois Central route down the Mississippi River valley.
21st century.
In 2014, freight transportation establishments serving for-hire transportation and warehousing operations employed nearly 4.6 million workers and comprised 9.5 percent of the Nation's economic activity as measured by GDP. Truck driving is by far the largest freight transportation occupation, with approximately 2.83 million truck drivers. About 57.5 percent of these professional truck drivers operate heavy or tractor-trailer trucks and 28.2 percent drive light or delivery service trucks.
According to "Freight Facts and Figures 2015", U.S. freight transportation system handled a record amount of freight in 2014. A daily average of approximately 55 million tons of freight valued at $49.3 billion moved across the transportation system in 2014 to meet the needs of the nation's 122.5 million households, 7.5 million business establishments, and 90,056 Government units.
Wartime expediency encouraged long distance pipeline transport of petroleum and natural gas, which was greatly expanded in the middle 20th century to take over most of the domestic long-haul market.
Road transportation.
Infrastructure and private automobile use.
In comparison to some parts of the Western world, both the United States and Canada rely more heavily on motorized transit over walking and bicycling with 86% of American workers commuting to work via private vehicle, costing an estimated additional $1500 per year commuting compared to Western European counterparts. Car ownership is on the decline but still 91% nationally. Car ownership is universal, except in the largest cities where extensive mass transit and railroad systems have been built, with lowest car ownership rates in New York City (44%), Washington, D.C. (62%), Boston (63%), Philadelphia (67%), San Francisco (69%), and Baltimore (69%).
With the development of the extensive Eisenhower Interstate Highway System in the 1950s, both long distance trips and daily commutes were mostly by private automobile. This network was designed to exacting federal standards in order