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73-471: Employment 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

146-533: A bipartisan infrastructure bill with about $ 110 billion for roads and bridges. As of 2010, seat belt use is mandatory in all states except New Hampshire . Seat belt use is also mandatory in Washington, D.C. , the national capital, and the five inhabited U.S. territories . Greyhound Lines is the largest intercity bus company in the United States, with routes in all parts of the contiguous U.S. There are also many smaller regional bus companies, many of which use

219-774: A conference in Havana , 57 airlines formed the International Air Transport Association . In 1948, Berlin was jointly controlled by the Western Allies and Soviet Union , although the Soviet Union held the area surrounding the city and thus land access. During the Berlin Blockade , this land access was closed, and an airlift remained the only option to get increasingly urgent deliveries of food, coal, and other supplies to West Berlin . Over 330 days to 12 May 1949

292-590: A designation created for the legacy highway network in 1995, comprising 160,000 miles (256,000 kilometers) of roadway, a fraction of the total mileage of roads. The Interstate system serves nearly all major U.S. cities, often through the downtown areas, which triggered freeway and expressway revolts in the 1960s and 1970s. The distribution of many goods and services involves Interstate highways at some point. Residents of American cities commonly use urban Interstates to travel to their places of work. The vast majority of long-distance travel, whether for vacation or business,

365-784: 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

438-488: 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

511-525: 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

584-471: A result of aging infrastructure and poor road conditions. The United States continues to follow a method of attempting to resolve congestion by widening roadways. From 1993 to 2017, the nation's largest 100 urbanized areas added 42% more freeway lane milage, despite population growing by only 32%. However, this policy of widening roadways resulted in a 144% increase in congestion, due to the concept of induced demand . The trucking industry (also referred to as

657-457: A shoe manufacturer and grouse for a restaurant. Cinema films were also a frequent consignment: original news’ bulletins were first carried to a central laboratory to make copies, and then distributed by air throughout Europe for their release in cinemas. Although there were a few attempts to organize air freight airlines from the 1920s on, the first commercial airlines that were all-cargo did not emerge until after World War II . In 1945, at

730-701: A size comparable to the major international carriers. There is currently no government regulation of ticket pricing, although the federal government retains jurisdiction over aircraft safety, pilot training, and accident investigations (through the Federal Aviation Administration and the National Transportation Safety Board ). The Transportation Security Administration provides security at airports. Air shipping Different cargo can be transported by passenger, cargo or combi aircraft: The first cargo flight took place on

803-506: A total of 2.26 million tons of cargo were airlifted to Berlin, an average of 6,800 tons a day, 80% by the US and 20% by the UK. Although freight traffic developed modestly, reaching only 800,000 tonnes worldwide by the mid-1950s, the world economy was hitting its post-World War II stride. Germany and Japan were emerging from their period of purgatory and were poised to take the world of business by storm,

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876-408: A very small part of total air traffic. For much of the first five post-war decades, most carriers saw it as a secondary activity, although there had always been specialized cargo airlines. Some passenger airlines have found the practice of carrying belly cargo to be a highly lucrative enterprise; in fact, it is estimated that 50% of all air freight is moved in this way, to the point where it has lessened

949-574: Is by the national road network; of these trips, about one-third (by the total number of miles driven in the country in 2003) utilize the Interstate system. In addition to the routes of the Interstate system, there are those of the U.S. highway system . These routes, which are unrelated to those of the National Highway System, are supplemented by State Highways , and the local roads of counties , municipal streets , and federal agencies, such as

1022-479: Is commonly measured in twenty-foot equivalent units (TEUs), rather than cargo weight, e.g. a TEU-km would be the equivalent of one twenty-foot container transported one kilometer. Transportation density can be defined as the payload per period, say passenger / day or tonne / day. This can be used as the measure of intensity of the transportation on a particular section or point of transportation infrastructure, say road or railway. This can be used in comparison with

1095-410: Is more favorable. Freight is measured in mass-distance . A simple unit of freight is the kilogram-kilometre (kgkm), the service of moving one kilogram of payload a distance of one kilometre. The metric units (pkm and tkm) are used internationally. (In aviation where United States customary units are widely used, the International Air Transport Association (IATA) releases its statistics in

1168-449: Is no single national flag airline ; passenger airlines in the United States have always been privately owned. There are over 200 domestic passenger and cargo airlines and a number of international carriers. The major international carriers of the United States are Delta Air Lines , American Airlines , and United Airlines . Low-cost carrier Southwest Airlines operates few international routes, but has grown its domestic operations to

1241-562: 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. 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%

1314-631: The Accelerated Bridge Program in Massachusetts , but after some debate no increase in federal funding. The I-5 Skagit River bridge collapse in 2013, caused by a collision with an over-height truck , highlighted fracture critical bridges in which the failure of only one structural member will lead to complete collapse. According to the National Bridge Inventory , there are at least 600,000 bridges of 20 feet or more in length in

1387-533: The American economy by transporting large quantities of raw materials , works in process , and finished goods over land—typically from manufacturing plants to retail distribution centers. Trucks are also important to the construction industry, as dump trucks and portable concrete mixers are necessary to move the large amounts of rocks, dirt, concrete, and other construction material. Trucks in America are responsible for

1460-451: The Bureau of Indian Affairs . The five inhabited U.S. territories also have their own road networks. There are approximately 4,161,000 miles (6,696,000 km) of roads in the United States, 2,844,000 miles (4,577,000 km) paved and 1,317,000 miles (2,120,000 km) unpaved. State highways are constructed by each state, but frequently maintained by county governments aided by funding from

1533-565: 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 )

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1606-725: The U.S. Environmental Protection Agency implemented revised emission standards for diesel trucks (reducing airborne pollutants emitted by diesel engines) which promises to improve air quality and public health. Within the United States: With adjacent countries: Each state has its own traffic code , although most of the rules of the road are similar for the purpose of uniformity, given that all states grant reciprocal driving privileges (and penalties ) to each other's licensed drivers. The United States has advanced air transportation infrastructure which utilizes approximately 5,000 paved runways. In terms of passenger traffic, 17 of

1679-654: The hours of service , which are regulations governing the driving hours of commercial drivers. These, and all other rules regarding the safety of interstate commercial driving, are issued by the Federal Motor Carrier Safety Administration (FMCSA). The FMCSA is also a division of the United States Department of Transportation (USDOT), which governs all transportation-related industries such as trucking, shipping , railroads , and airlines . Some other issues are handled by another branch of

1752-436: The unit of measurement used to express various transportation quantities , as used in statistics, planning, and their related applications. The currently popular units are: Passenger-distance is the distance (km or miles) travelled by passengers on transit vehicles ; determined by multiplying the number of unlinked passenger trips by the average length of their trips. Passengers per hour per direction (pphpd) measures

1825-623: The 1990s there have been some small experiments with toll roads operated by private companies. After the collapse of the I-35W Mississippi River bridge in Minnesota in August 2007, the backlog of road and bridge maintenance across the country became an issue in transportation funding. The collapse prompted a tax increase in Minnesota to speed up bridge repairs, and action in other states, such as

1898-484: 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

1971-410: The 46,000 mile (75,000 km) nationwide Interstate highway network. Changes by state initiative may be made with federal approval. A large number of expressways are actually government or privately operated toll roads in many East Coast and Midwestern states. West Coast freeways are generally free to users, which is the basis of their name, since freeways have no toll charged per use, although since

2044-548: The 7 November 1910 in the U.S. between Dayton and Columbus in Ohio . Philip Orin Parmelee piloted a Wright Model B aeroplane 65 miles (105 km) carrying a package of 200 pounds of silk for the opening of a store. Newspaper clippings quoted the Wright brothers as stating he covered the distance in 66 minutes, but the flight was officially recorded at 57 minutes, a world speed record at

2117-490: 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

2190-809: The Minnesota Department of Public Safety, Office of Traffic Safety Volume of traffic, or vehicle miles traveled (VMT), is a predictor of crash incidence. All other things being equal, as VMT increases, so will traffic crashes. The relationship may not be simple, however; after a point, increasing congestion leads to reduced speeds, hanging the proportion of crashes that occur at different severity levels. Energy efficiency in transport can be measured in L/100 ;km or miles per gallon (mpg). This can be normalized per vehicle, as in fuel economy in automobiles , or per seat, as for example in fuel economy in aircraft . MacNeal 1994 discusses

2263-578: The USDOT, the Federal Highway Administration (FHWA). Developments in technology, such as computers, satellite communication , and the internet, have contributed to many improvements within the industry. These developments have increased the productivity of company operations, saved the time and effort of drivers, and provided new, more accessible forms of entertainment to men and women who often spend long periods of time away from home. In 2006,

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2336-425: The United States . 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

2409-679: 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

2482-452: 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

2555-453: The United States was approaching the height of its economic dominance, and Western Europe had recovered from the war. In 1968, Boeing launched the four engine 747 , the first wide-body aircraft . The 747 was the first aircraft capable of transporting full pallets in the cargo hold, revolutionizing the air cargo industry. Despite widespread hopes for a vibrant industry, for decades the air freight sector did not grow as expected and remained

2628-533: The United States, all subject to deterioration in the absence of preventative maintenance. In December 2008, 72,868 bridges in the United States (12.1%) were categorized as "structurally deficient", representing an estimated $ 48 billion in repairs. President Barack Obama proposed $ 50 billion of spending on road and bridge repair, plus a national infrastructure bank, but Congress did not act on these proposals. President Donald Trump also failed to get infrastructure funding approved. In 2021, President Joe Biden signed

2701-459: The United States, the unit is used as an aggregate in yearly federal publications, while its usage is more sporadic in other countries. For instance, it appears to compare different kind of roads in some publications as it had been computed on a five-year period between 1995 and 2000. In the United States, it is computed per 100 million miles traveled, while internationally it is computed in 100 million or 1 billion kilometers traveled. According to

2774-422: 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. The advent of the automobile signaled the end of railroads as the predominant transportation for people and began

2847-638: The air cargo industry continues to suffer as the by-product 'poor-relation' of the passenger business. In 2017, the IATA observed a 9% rise in freight tonne kilometers : air cargo demand is strong due to industrial production and global trade growth above expansion of e-commerce , outpacing capacity as available tonne kilometers grew by 3%. Boeing doubled its 767F production since 2016 to three per month in 2020, and anticipates that total global air cargo traffic will more than double by 2041. Ton-mile The units of measurement in transportation describes

2920-524: The aviation display, Walter Windham , was able to secure permission from the postmaster general in India to operate an airmail service in order to generate publicity for the exhibition and to raise money for charity. This first airmail flight was piloted by Henri Pequet , who flew 6,500 letters a distance of 13 km (8.1 mi), from Allahabad to Naini —the nearest station on the Bombay-Calcutta line to

2993-548: The building of canals to speed goods to market. One such prominent example was the Erie Canal . 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

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3066-407: The construction, running costs of the infrastructure. Fatalities by VMT ( vehicle miles traveled ) is a unit for assessing road traffic fatalities. This metric is computed by dividing the fatalities by the estimated VMT. Usually, transport risk is computed by reference to the distance traveled by people, while for road traffic risk, only vehicle traveled distance is usually taken into account. In

3139-502: 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

3212-461: The demand for dedicated large cargo aircraft. Cargo emerged as a solid pillar of the industry in the 1990s. The catalysts for the renewed growth in the sector were the express parcel carriers, typified by FedEx , DHL , PostNL , and UPS , and changes in practices in the manufacturing sector. In 1992, FedEx sent software on computer disks to thousands of customers, allowing them to track shipments from their own workstations. The rise of internet in

3285-516: 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 to receive federal funding. The system, as of 2010, has a total length of 47,182 miles (75,932 km), making it the world's second longest after China 's, and the largest public works project in US history. The Interstate system joined an existing National Highway System ,

3358-422: 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

3431-647: The exhibition. The aircraft used was a Humber-Sommer biplane with about fifty horsepower (37 kW), and it made the journey in thirteen minutes. The world's first scheduled airmail post service took place in the United Kingdom between the London suburb of Hendon , and the Postmaster General 's office in Windsor, Berkshire , on September 9, 1911. It was part of the celebrations for King George V 's coronation and at

3504-515: 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) [1] 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

3577-533: 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

3650-650: 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). 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

3723-472: 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

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3796-480: 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

3869-401: The majority of freight movement over land, and are vital tools in the manufacturing, transportation, and warehousing industries. Large trucks and buses require a commercial driver's license (CDL) to operate. Obtaining a CDL requires extra education and training dealing with the special knowledge requirements and handling characteristics of such a large vehicle. Drivers of CMVs must adhere to

3942-439: The maximum route capacity of a transport system. A system may carry a high number of passengers per distance (km or mile) but a relatively low number of passengers per bus hour if vehicles operate in congested areas and thus travel at slower speed. A transit system serving a community with a widely dispersed population must operate circuitous routes that tend to carry fewer passengers per distance (km or mile). A higher number

4015-426: The metric units.) In the US, sometimes United States customary units are used. The dimension of the measure is the product of the payload mass and the distance transported. A semi truck traveling from Los Angeles to Chicago (approximate distance 2,015 miles) carrying 14 short tons of cargo delivers a service of 14 * 2,015 = 28,210 ton-miles of freight (equal to about 41,187 tkm). Intermodal container traffic

4088-639: 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

4161-512: The package and cargo delivery market. 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 115% more road fatalities in the US than in the European Union, or 53% less in the EU than in the US, with nearly 38,680 in the US, and nearly 18,800 in the EU. In

4234-452: The past decade, and despite the declining traffic volumes caused by the economic downturn, Americans still waste more than 2.8 billion US gallons (11 million cubic metres) of fuel each year as a result of traffic congestion. Motorists also waste 4.2 billion hours annually, or one full workweek per traveler. Moreover, it is estimated that drivers are wasting 6.9 billion hours per year or about 42 hours per driver in traffic congestion as

4307-437: 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

4380-557: 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

4453-421: The security and safety of the transportation. Many retailers are making an effort to integrate the air cargo delivery process with their customer service offering to respond to increasing consumer pressure. An industry expert estimates that 15-20 tonnes of air cargo is worth 30-40 economy passenger seats, when both are on passenger planes. However, with the exception of the integrators (FedEx, UPS, DHL and TNT)

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4526-496: The state, where such counties exist as governing entities in mostly every state outside of the northeast . Counties construct and maintain all remaining roads outside cities, except in private communities. Local, unnumbered roads are often constructed by private contractors to local standards, then maintenance is assumed by the local government. All federal highways are maintained by state governments, although they receive federal aid to build and maintain freeways signed as part of

4599-502: The suggestion of Windham , who based his proposal on the successful experiment he had overseen in India. The service ran for just under a month, transporting 35 bags of mail in 16 flights. In the early 1920s, air cargo developed rapidly because numerous entrepreneurs realized aircraft could move high value and low volume consignments much faster than the railroads and shipping companies. The first scheduled flight from London to Paris in 1919 had only one passenger, but carried leather for

4672-435: The terminal and booking facilities provided by Greyhound. Intercity bus is, in most cases, the least expensive way to travel long distances in the United States. Traffic congestion, especially at rush hour, is often considered a problem in many of the country's larger cities. A 2009 study claimed that traffic congestion costs the United States almost $ 87.2 billion. The economic costs of traffic congestion have increased 63% over

4745-508: The time. It was the first "cargo only" flight solely for the transport of goods; the first flight commissioned by a client, and the first example of multimodal air transport, since the pieces of silk were transported by car from Columbus aerodrome to the store. The world's first official airmail flight by airplane took place on 18 February 1911, at a large exhibition in the United Provinces of Agra and Oudh , British India . The organizer of

4818-434: 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

4891-423: The transportation or logistics industry) involves the transport and distribution of commercial and industrial goods using commercial motor vehicles (CMV). In this case, CMVs are most often trucks ; usually semi trucks , box trucks , or dump trucks . A truck driver (commonly referred to as a "trucker") is a person who earns a living as the driver of a CMV. The trucking industry provides an essential service to

4964-470: 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. In comparison to some parts of the Western world , both

5037-515: The west, and CSX and Norfolk Southern in the east. Canadian National Railway took over the Illinois Central route down the Mississippi River valley. 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

5110-467: The world's 30 busiest airports in 2004 were in the United States, including the world's busiest, Hartsfield-Jackson Atlanta International Airport . In terms of cargo, in the same year, twelve of the world's thirty busiest airports were in the United States, including the world's busiest, Memphis International Airport . Private aircraft are also used for medical emergencies, government agencies, large businesses, and individuals, see general aviation . There

5183-401: The years that followed contributed to increase the reliability and accessibility to the air cargo industry. Most airlines now offer to their customers real-time flight status and the booking and tracking options. In addition, the industry is adopting electronic procedures , such as the electronic air waybill , to reduce the amount of paper documentation accompanying each shipment and increasing

5256-410: 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

5329-464: 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

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