The U.S. freight transportation system moved nearly 18.1 billion tons of goods valued at more than $19.2 trillion in 2015, according to Freight Analysis Framework (FAF) estimates (table 3-1). This means the freight transportation system carried, on average, about 49.5 million tons of goods worth more than $52.7 billion each day, or about 56 tons of freight annually per capita in the United States in 2015, a 4.0 percent increase from 2012. See box 3-A for information about the FAF and its foundation, the Commodity Flow Survey (CFS).

In 2015 freight tonnage and value rose 6.5 and 8.2 percent, respectively, over 2012. Table 3-1 shows that the total weight and value of freight in 2015 surpassed 2012 levels in all categories, except import tonnage. The most recent long-range FAF forecasts show that freight tonnage will grow about 1.2 percent annually between 2015 and 2045. The value of goods transported, in real dollars, is projected to increase faster than tonnage and might nearly double during this time span as higher value goods are moved [USDOT BTS and FHWA FAF 2016].

U.S. exports and imports accounted for 5.1 and 6.1 percent of the weight and 8.8 and 12.9 percent of the value of freight transported in 2015, respectively. FAF forecasts that U.S. exports and imports will account for an even greater share of freight movements in 2045, reaching 17.5 percent of the weight and 39.3 percent of the value of goods shipped throughout the country [USDOT BTS and FHWA FAF 2016].

Population growth and economic activity continue to be the primary factors that determine freight demand. As population increases or economic activity expands, more goods are produced and used, resulting in additional freight movement. Between 2010 and 2015, the U.S. population increased by 3.9 percent [USDOC CENSUS American Fact Finder], and U.S. gross domestic product grew by 10.9 percent in terms of chained 2009 dollars [USDOC BEA 2016]. In addition, changes in the composition of goods demanded and shifts of economic centers to Asia had an effect on what goods were moved, what modes were used to transport them, and where they were shipped. Freight carried by the for-hire transportation industry rose as the economy rebounded from the past recession. With a freight Transportation Services Index of 122.3, freight shipments in June 2016 were 29.1 percent above the index low of 94.7 recorded in April 2009, during the recession, and are up by 8.2 percent in the 10 years from June 2006 [USDOT BTS 2016a].

How Domestic Freight Moves

The freight transportation industry moves goods over a network of truck routes, railroads, waterways, airports, and pipelines. The distance a shipment must travel, either by single mode or during any particular leg of a multimodal journey, plays a major part in determining what mode or modes are used.

Overall, trucks carry the highest percentage of the weight and value of goods in the United States, accounting for 60.1 and 60.8 percent, respectively, in 2015. However, figure 3-1 shows that railroads and inland waterways carry large volumes and tonnages of bulk commodities, like coal and petroleum products, over long distances. Rail and water combined accounted for 14.1 percent of the total tonnage and 6.5 percent of the total value of freight moved in the United States in 2015. Air carriers moved high-value, low- weight products. This is underscored by the relatively extreme value-to-weight ratio of air cargo, which is about $108,500 per ton. In comparison, the overall value-to-weight ratio of cargo carried by all modes combined is less than $1,100 per ton. In 2015 pipelines moved nearly 3.3 billion tons of goods valued at about $1.4 trillion ($433 per ton), while rail moved more tonnage of lesser value—1.6 billion tons valued at $617 billion ($384 per ton). [USDOT BTS and FHWA 2016].

Shipments moving by water are typically low-value, bulk products similar to rail.¹  In 2015 the water transportation industry moved 936 million tons worth $636 billion (nearly $680 per ton), representing 5.2 percent of the tonnage and 3.3 percent of the value of all freight shipments [USDOT BTS and FHWA 2016]. In 2015 approximately 565 million short tons of cargo were moved by vessel along the inland waterways, including the Mississippi River—the Nation’s busiest waterway [USACE WCSC 2016a].

In comparison with the rail and water modes, air transport carries high-value products, such as electronics, precision instruments, and pharmaceuticals that require quick delivery. Of all modes, the value of air-freight shipments is projected to increase the fastest from 2015 to 2045, growing by more than 300 percent [USDOT BTS and FHWA 2016]. In 2015 U.S. airlines² carried a total of 65,092 million international and domestic freight and mail cargo revenue ton-miles, of which 13,190 million were domestic [USDOT BTS 2016c].

Over the last 20 years, the U.S. transportation system has become increasingly interconnected. Although multimodal services accounted for a small share (7.5 percent) of freight tonnage, they moved 18.7 percent of the value of the goods in 2015. FAF forecasts the total value of multimodal shipments will more than double between 2015 and 2045 [USDOT BTS and FHWA 2016].³

The growth in intermodal freight movement is driven, in part, by global supply chain requirements. Between 2000 and 2015, the railroad industry reported a 50.5 percent increase in trailer and container traffic [AAR 2016b]. The Association of American Railroads reports that rail intermodal traffic accounted for 13.0 percent of U.S. Class I railroad revenue in 2015. Only coal and chemicals and allied products accounted for a larger share of revenue [AAR 2016a]. With the growth in container trade and improvements in information and logistics technologies, the stage is set for even greater reliance on intermodal transportation to move goods from manufacturers to consumers.

Value and Weight of Domestic Shipments by State

An interconnected freight transportation network contributes to state economic growth by supporting resource development and expanding interstate commerce. Figures 3-2 and 3-3 show the ratios of the value and weight of goods shipped to and from other states. A ratio greater than 1.0 indicates that a state ships more goods to markets in other states than it receives from other states, whereas a ratio less than 1.0 indicates that a state imports more goods from other states than it exports.

By value, Alaska and North Dakota have the highest ratio of about 2.0, indicating these states export more goods to other states than they import. Both states are major oil producers and exporters while their relatively small populations require fewer imports than other states. According to the FAF, the water mode moved nearly all of Alaska-produced oil to California in 2015, while pipeline and rail were the primary modes for moving oil out of North Dakota. Other major states that export more than they import were California, Connecticut, and Illinois. Electronics was the top outbound domestic shipment category from California, accounting for 20.5 percent of its total exports to other states, while mixed freight was the leading outbound shipment from Connecticut at 20.0 percent. Mixed freight includes items such as grocery and convenience store goods, food for restaurants, office supplies, and hardware and plumbing items. Coal was the top outbound shipment from Illinois, accounting for 9.8 percent of its exports to other states. Hawaii had the lowest ratio of interstate outbound-to- inbound shipments by value at 0.16 because of its geography. Other states that import more than they export by value include Florida and Arizona, partly due to demographics [USDOT BTS and FHWA 2016].

The picture changes when looking at the ratio of outbound to inbound shipments by weight. All of the top five domestic net exporters are major producers of energy commodities: Wyoming, Alaska, Montana, North Dakota, and West Virginia. Wyoming is the largest coal producer, followed by West Virginia, while Montana is the sixth largest coal producer, according to the Energy Information Administration. For domestic markets, rail and barge are used to transport coal over longer distances, primarily to power plants.

For all 50 states (excluding the District of Columbia), an average of 44.3 percent of shipments by value were moved to a destination within state. Trucks accounted for 80.8 percent of intrastate shipments. Hawaii had the highest percentage of intrastate shipments by value (91.9 percent), most of which were transported by truck, followed by Texas (70.9 percent), and Florida (67.6 percent). By value, Nevada had the lowest percentage of intrastate shipments (29.2 percent). Nevada’s textile/leather industry moved 88.2 percent of its products to markets outside the state.

Commodities Moved Domestically

Table 3-2 shows the top 10 commodities moved on the U.S. transportation system in 2015. The leading commodities by weight, comprised entirely of bulk products, accounted for 67.5 percent of total tonnage but only 25.6 percent of the Nation’s freight value. The top 10 commodities included natural gas, coke,⁴ and asphalt; gravel; gasoline; cereal grains; and nonmetal mineral products [USDOT BTS and FHWA 2016].

The story is different when looking at the value of goods shipped. The leading commodities by value are high value-per-ton goods that require more rapid delivery, including electronics, motorized vehicles, mixed freight, machinery, and gasoline. In 2015 the top 10 commodities by value accounted for 57.5 percent of total value but only 36.2 percent of total tonnage [USDOT BTS and FHWA 2016].

Energy Commodities Transportation

The delivery of energy commodities involves various modes, depending on the characteristics of the commodity and the distances from wellhead or mine to processing facilities and then to the final consumer. Increasingly, energy commodity movements are multimodal, utilizing a combination of pipeline, rail, barge, and truck. The transportation of crude oil and refined petroleum products, coal, and ethanol are discussed here.

In recent years, advances in hydraulic fracturing have opened new areas to oil and gas development, creating new demands for the transportation of energy commodities. Box 3-B discusses hydraulic fracturing and its implications for the freight transportation system.

Crude Oil and Petroleum Refined Products

Pipelines are the primary mode for transporting crude oil and petroleum products in the United States. Historically, pipelines delivered crude oil from offshore platforms in the Gulf of Mexico to nearby refineries, but changes in where oil is produced have affected transportation patterns in recent years. For example, expanded production in regions distant from refineries, such as the Bakken formation in North Dakota, has increased the use of rail, barges, and trucks to move oil from the wellhead to refineries. In addition to continuing their historic role of delivering crude oil from the Gulf of Mexico to refineries, pipelines also move domestic and Canadian crude oil to the Gulf of Mexico to be refined and/or exported [USDOE 2015]. U.S. crude oil production increased by 72.2 percent, from nearly 2.0 billion barrels in 2010 to more than 3.4 billion barrels in 2015 (figure 3-4). Texas and North Dakota accounted for 49.1 percent of U.S. crude oil production in 2015.

Expanded oil production also has spurred growth in the waterborne transport of oil. According to the U.S. Army Corps of Engineers, U.S. ports and inland waterways handled more than 7 billion barrels of domestic and international crude oil (48.3 percent) and petroleum products (51.7 percent) in 2014, the latest year for which data are available [USACE NDC 2016]. In comparison, pipelines transported about twice the total volume handled by ports and inland waterways in 2014 [AOPL].

The use of tankers and barges for oil transport on U.S. inland waterways, from port to port along the coasts or on the Great Lakes, also has increased in recent years from about 2.6 percent (15.7 billion barrels) of modal share in 2010 to 3.3 percent (40.0 billion barrels) in 2015, after peaking at 6.8 percent (59.0 billion barrels) in 2013. A significant share of oil transport is intermodal; for example, oil is transported by pipeline or rail to a terminal and then transferred to a barge for delivery to a refinery.

Trucks are used for short-haul drayage of crude oil from the wellhead to gathering pipelines or rail loading terminals for long-distance transport. Because oil production has outpaced the construction of pipeline gathering systems in the Bakken region, trucks deliver about 40 percent of Bakken oil to pipeline and rail terminals, according to DOE [USDOE 2015]. Trucks also are used to move crude oil over short distances to refineries. The demand for truck transport is illustrated by the more than tripling of refinery receipts of crude oil by truck, from 50.6 million barrels in 2000 to nearly 176.7 million barrels in 2015 [USDOE EIA 2015c].

After the crude oil is refined into gasoline, diesel fuel, jet fuel, and heating oil, among other products, these commodities are shipped via pipeline to a bulk storage terminal that serves many companies. Gasoline, for example is loaded on tanker trucks for delivery to various retail gas stations. Jet fuel is pumped directly from the storage terminal to major airports that have receiving facilities on site.

Coal

How coal is transported depends on the distance it must travel. Typically trucks are used for short distances, while trains and barges are used for longer hauls. According to FAF, rail moved the greatest share of domestic coal shipments in 2015, accounting for 64.9 percent (565 million short tons) of the total 870.6 million short tons (figure 3-5), which is a 33 percent drop from the 1.3 billion tons moved by rail in 2012. Nearly 70 percent of coal used to generate electricity is delivered to power plants by rail [USDOE EIA 2016e]. Approximately two-fifths of all U.S. coal is produced in Wyoming’s Powder River Basin. The vast majority of Wyoming’s coal is sent to power plants in 33 states, and almost all of that tonnage is moved by rail [USDOE EIA 2015].

The Association of American Railroads reports that coal represents 36.9 percent of total tonnage moved by rail and 17.2 percent of U.S. Class I railroad gross revenue in 2015 [AAR 2016a]. Many in the railroad industry view coal as its most important single commodity.

Trucks are the second largest mover of domestic coal shipments, hauling 20.5 percent (nearly 179 million short tons) (figure 3-6). Inland waterways are also an important transportation option for coal shipments—292 million tons of coal, lignite, and coke were moved in 2014 [USACE NDC 2015]. Barges typically have the lowest transportation prices per ton, but they are limited by access to navigable waterways and cannot take coal everywhere that it is needed.

Ethanol

U.S. ethanol production has grown steadily from 38.6 million barrels in 2000 to 352.5 million barrels in 2015 [USDOE EIA 2016a]. Ethanol now displaces approximately 10 percent of U.S. gasoline demand by volume. Ethanol production is primarily located in the Midwest where most of the corn feedstocks are grown and delivered by trucks from farms or grain storage facilities to ethanol production plants. Typically, rail moves ethanol from production plants to distribution terminals, which accounts for 60–70 percent of ethanol shipments. Nearly 304,000 carloads of ethanol were transported by railroads in 2013 (latest year for which data are available), up from fewer than 40,000 carloads in 2000, according to the American Association of Railroads (AAR). In 2013 ethanol shipments accounted for 1.0 percent of total rail carloads and 1.4 percent of rail ton-miles (AAR 2015]. Most ethanol shipments carried by railroads move in 30,000-gallon tank cars, almost all of which are owned by shippers or leasing companies. The blending of ethanol with gasoline takes place at petroleum product distribution terminals across the country, and the final product is delivered by truck to retail outlets.

Hazardous Materials

As measured by the CFS, nearly 2.6 billion tons of hazardous materials, valued at approximately $2.3 trillion, were moved within the United States in 2012, an increase of 15.6 percent over 2007 tonnage, due in part to expanded coverage [USDOT BTS and USDOC Census 2015]. Trucks moved 59.4 percent of the weight and 62.8 percent of the value of all hazardous materials shipments in 2012. This represents an increase in truck’s share of total tonnage by 5.5 percent. Pipelines moved 24.3 percent of hazardous materials tons in 2012, slightly less than its share in 2007; while waterways and rail handled 11.0 and 4.3 percent, respectively, of total hazardous materials shipments by weight (table 3-3).

Hazardous materials were shipped over 307.5 billion ton-miles in 2012, a 4.9 percent decrease from 2007. In comparison to its share of tonnage and value moved, trucks accounted for a smaller share of ton-miles—31.4 percent—because of the relatively short distances these products were transported. Across all modes, hazardous materials shipments were moved an average of 114 miles in 2012, with truck shipments moving about half the average distance (56 miles). Rail accounted for 27.6 percent of hazardous materials ton-miles, with an average distance per shipment of 808 miles in 2012, compared to 578 miles in 2007—a nearly 40 percent increase.

Of the nine classes of hazardous materials, flammable liquids accounted for the largest share by value (86.4 percent) and by tons (85.4 percent), followed by gases, a distant second (table 3-4). Hazardous materials transport poses risks to public safety and the environment. In recent years, several accidents in the United States and Canada involving explosions, fires, and leaks from rail tank cars have heightened concern about public safety in communities through which these cars pass as well as the environmental risks surrounding the transport of these materials. In 2016 BTS established a railroad tank car safety data program to track the number of rail tank cars retrofitted to meet enhanced safety standards. Chapter 8 discusses this and other BTS programs to support transportation safety goals.

International Trade

The value of total U.S.-international merchandise trade increased from more than $2.4 trillion in 2000 to approximately $3.4 trillion in 2015—a 40.1 percent inflation- adjusted increase [USDOC Census FTD 2016]. Five of the top 10 U.S. trading partners were Asian countries in 2015. Trade with China grew the fastest, from 5.8 percent of the total value of U.S. merchandise trade in 2000 to 16.0 percent in 2015. In 2000 China ranked fourth among U.S. trading partners. Today it is the leading U.S. trade partner, followed by Canada, Mexico, Japan, and Germany, respectively rounding out the top five [USDOC Census ITA].

In 2015 vessels carried $1.6 trillion in imports to and exports from the United States [USDOC Census FTD 2016]. U.S. retailers are increasingly dependent on the U.S. transportation system, especially those that build up their inventories in October in anticipation of holiday sales in November and December. In particular, businesses use liner⁵ services to move intermodal shipping containers through the global transportation system. Container ports provide a link between the global and domestic freight network, utilizing intermodal barge, truck, and rail connections to transport containers to their final destinations [CHAMBERS 2012].

U.S. Freight Trade with Canada and Mexico

The U.S. North American Free Trade Agreement (NAFTA) partners—Canada and Mexico—accounted for 29.6 percent ($1.0 trillion in inflation-adjusted dollars) of the value of U.S.-international merchandise trade in 2015. Over the 2000 to 2015 period, combined trade (adjusted for inflation) with Canada and Mexico increased 26.7 percent⁶ [USDOC Census FTD 2016]. However, from 2014 to 2015, the value of cross-border freight declined by 7.2 percent, largely due to a drop in crude oil and petroleum product prices. The value of petroleum-related commodity shipments declined by almost 40 percent year-over-year, while the value of other freight dropped 0.9 percent [USDOT BTS 2016b].

In 2015 U.S. imports from Canada and Mexico exceeded exports in terms of total merchandise trade value. Imports totaled nearly $5.9 billion in 2015, an increase of 28.8 percent since 2005. While the value of imports outpaced exports over that period, the value of U.S. exports to Canada and Mexico also continued to grow, increasing by 55.8 percent since 2005 (figure 3-7) [USDOT BTS 2016b].

Trucks carried 25.6 percent of the tonnage and 64.3 percent of the value of U.S. merchandise trade with Canada and Mexico, while rail carried 18.3 percent of the tonnage and 14.9 percent of the value in 2015 (table 3-5). Vehicles and parts (other than railway vehicles and parts) was the top commodity category transported between the United States and Canada. The truck and rail modes transported 60.0 and 37.5 percent, respectively. Mineral fuels and oil were the next highest commodity category, transported primarily by the pipeline and water modes [USDOT BTS 2016b].

Michigan, which accounts for 13.0 percent of the U.S.-Canada border mileage, was the leading state for trade with Canada, amounting to $69.1 billion or 12.0 percent of total trade with Canada in 2015. Michigan has border crossing/entry ports between Detroit, Port Huron, and Sault Ste. Marie and southern Ontario; both Michigan and Ontario have a high concentration of automakers [USDOT BTS 2016b].

Texas, which accounts for 64.2 percent of the U.S.-Mexico border mileage and is home to 11 border crossing/entry ports, led all other states in surface freight with Mexico [USDOT BTS 2016a]. (In total, there are 87 ports-of- entry along the U.S.-Canada border and 25 on the U.S.-Mexico border.) In 2015 Texas trade with Mexico amounted to nearly $178.0 billion, or 33.5 percent of total U.S. trade with Mexico. Electrical machinery, equipment, and parts was the top commodity category transported between the United States and Mexico, followed by vehicles and vehicle parts (other than railway vehicles and parts). Truck is the primary mode for transporting electrical machinery while rail moves the bulk of vehicles [USDOT BTS 2016b].

Freight Transportation Gateways

A large volume of U.S.-international merchandise trade passes through a relatively small number of freight gateways—the entry and exit points for trade between the United States and other countries (figure 3-8). According to the Census Bureau, there were 480 ports of entry, including airports, border crossings, and seaports that could handle international cargo [USDOC Census FTD 2016], while the latest available data show that in 2014 the top 25 gateways in terms of value handled the greatest share of U.S. international merchandise trade—$2.5 trillion in current dollars or 63.0 percent of the more than $3.9 trillion (in current dollars) in total U.S.- international merchandise trade in that year. Eighteen of the top 25 gateways handled more imports than exports in 2014, compared to 17 in 2013.

Water is the leading transportation mode for U.S.-international trade both in terms of weight and value. Ships moved more than 71.1 percent of trade weight and 41.8 percent of trade value in 2015 (figure 3-9). The Port of South Louisiana was the top water gateway by weight in 2014 (the latest year for which data are available), handling 267.4 million short tons, followed by the Port of Houston, moving 234.3 million short tons (USACE WCSC 2016b]. A considerable portion of this tonnage included crude oil and petrochemicals. By value, the Port of Los Angeles was the leading water gateway, handling more than $215.0 billion in cargo, mostly imports, while on the Atlantic coast the Port of New York and New Jersey ranked second with $206.5 billion in trade [USDOT BTS 2016d].

Air handles less than 1.0 percent of trade weight but 26.6 percent of trade value, due to its focus on high-value, time-sensitive, and perishable commodities. In 2014 John F. Kennedy International airport was the top U.S.-international air gateway by value, handling $191.8 billion in exports and imports, followed by Chicago area airports ($134.0 billion) and Los Angeles International ($92.4 billion) [USDOT BTS 2016d]. By freight tonnage, Memphis International, TN, Ted Stevens Anchorage International, AK, and Louisville International, KY, were the top U.S.-international air gateways, handling about 11.4 million, 7.9 million, and 5.8 million short tons of cargo, respectively, in 2014 [USDOT FAA].

Trucks, which haul a large share of imports and exports between U.S. international gateways and inland locations, carried 19.0 percent of the value of total U.S.-international trade (figure 3-9a) and 10.1 percent of the tonnage in 2015 (figure 3-9b). Laredo, TX, is the top land-border crossing, handling $192.1 billion in trade between the U.S. and Mexico while Detroit, MI, ranked second with $133.0 billion [USDOT BTS 2016d].

Trade growth with Canada and Mexico and the tapping of natural resources, such as oil from the Bakken formation, generates increased north-south traffic flows on a domestic transportation infrastructure that was initially developed along east-west corridors during the westward development of the Nation.

Water Trade

As a result of the growth in international trade, the number of container vessels calling at U.S. ports has increased. Between 2013 and 2015, vessel calls at U.S. seaports increased by 11.0 percent, from 74,000 in 2013 to 82,000 in 2015. The average displacement of container vessels continued to increase, from 44,601 deadweight tons (dwt) in 2005 to 57,458 dwt in 2015, a 28 percent increase. In 2015 tankers accounted for 40.4 percent of the vessel calls, followed by containerships with 22.8 percent of the more than 82,000 vessel calls [USDOT MARAD 2016a].

In 2015 U.S. seaports handled approximately 32.0 million TEU of containerized cargo, which is 12.0 percent more than reported in 2010 [USDOT MARAD 2016b]. The ports of Los Angeles and Long Beach on the Pacific coast and the port of New York and New Jersey on the Atlantic coast are the leading container ports. As shown in figure 3-10, the geographic distribution of container ports is more concentrated along the Pacific and Atlantic coasts, while large volumes of bulk commodities are transported through Gulf coast ports (figure 3-1).

The major increase in trade with China has resulted in a large share of trade moving through Pacific coast ports (figure 3-11). The trend toward larger containerships, which is expected to continue, has led to a concentration of liner service at ports with ample overhead clearance and water draft, intermodal connections such as double stack rail, and room to grow. The newly expanded Panama Canal allows larger vessels, carrying up to 13,000 TEU, to transit between the Atlantic and Pacific Oceans. Box 3-C discusses the effects the Panama Canal expansion may have on U.S. ports and trade patterns.

References

Association of American Railroads (AAR):

—2016a Class I Railroad Statistics (May 3). Available at http://www.aar.org/ as of March 2016.

—2016b. Rail Intermodal Keeps America Moving. May. Available at http://www.aar.org/ as of June 2016.

—2015. Railroads and Ethanol. July. Available at http://www.aar.org/ as of March 2016.

—2013. Moving Crude Oil by Rail. May. Available at http://www.aar.org/ as of April 2016.

Association of Oil Pipelines (AOPL). U.S. Liquid Pipeline Usage and Mileage Report. Available at http://www.aopl.org as of April 2016.

Network for Public Health Law (NPHL). 2011. The Impact of Hydraulic Fracturing on Communities. Available at https://www. networkforphl.org as of May 2016.

North Dakota Pipeline Authority (NDPA). 2016. June 2016 Monthly Update, June 2016 Production & Transportation. August 12. Available at http://www.northdakotapipelines.com/ as of August 2016.

Panama Canal Authority (PCA). 2015. Transit Statistics, Fiscal Year 2015. October 13. Available at http://www.pancanal.com/ as of April 2016.

Upper Great Plains Transportation Institute (UGPTI). 2014. Traffic Growth and Transportation Safety in the Bakken Oil Producing Region. Available at http://www. ugpti.org/ as of May 2016.

U.S. Army Corps of Engineers (USACE), Institute for Water Resources (IWR). 2012. U.S. Port and Inland Waterways Modernization: Preparing for Post-Panamax Vessels. June 20. Available at http://www.iwr. usace.army.mil/ as of April 2016.

U.S. Army Corps of Engineers (USACE), Navigation Data Center (NDC):

—2016. Commodity Movements from the Public Domain Database. Available at www. navigationdatacenter.us as of April 2016.

—2015. Waterborne Commerce of the United States, Calendar Year 2014. April 12. Available at www.navigationdatacenter.us as of April 2016.

U.S. Army Corps of Engineers (USACE), Waterborne Commerce Statistics Center (WCSC):

—2016a. Preliminary Waterborne Commerce Statistics for Calendar Year 2015—Waterborne Commerce National Totals and Selected Inland Waterways for Multiple Years. September 1. Available at http://www.navigationdatacenter. us as of September 2016.

2016b. Tonnage for Selected U.S. Ports in 2014. Available at www.navigationdatacenter. us as of June 2016.

U.S. Department of Commerce (USDOC), Bureau of Economic Analysis (BEA). 2016. News Release 16-40: National Income and Product Accounts--Gross Domestic Product: Second Quarter of 2016 and Annual Update: 2013 through Frist Quarter 2016, Table 3B. July 29. Available at http://www.bea.gov/ as of April 2016.

U.S. Department of Commerce (USDOC), Census Bureau (Census):

—Foreign Trade Division (FTD). 2016. FT920 - U.S. Merchandise Trade: Selected Highlights. Available at http://www.census.gov/ as of August 2016.

—International Trade Administration (ITA). TradeStats Express. Available at http://tse. export.gov/ as of April 2016.

—Population Estimates. Available at http:// www.census.gov/ as of March 2016.

U.S. Department of Energy (USDOE). 2015. The Quadrennial Energy Report. April. Available at http://www.energy.gov/ as of April 2016.

U.S. Department of Energy (USDOE), Energy Information Administration (EIA):

—2016a. Monthly Energy Review. June. Available at http://www.eia.gov/ as of June 2016.

—2016b. Refinery Receipts of Crude Oil by Method of Transportation. June 22. Available at http://www.eia.gov/ as of August 2016.

—2016c. Movements of Crude Oil and Selected Products by Rail. May 31. Available at http://www.eia.gov/ as of June 2016.

—2016d. Today in Energy. “Hydraulic fracturing accounts for about half of current U.S. crude oil production.” March 15, 2016. Available at http://www.eia.gov/ as of May 2016.

—2016e. Today in Energy. “Rail continues to dominate coal shipments to the power sector.” February 24. Available at http://www.eia.gov/ as of March 2016.

—2015. Wyoming, State Profile and Energy Estimates. December 17. Available at http:// www.eia.gov/ as of April 2016.

U.S. Department of Transportation (USDOT), Bureau of Transportation Statistics (BTS) and U.S. Department of Commerce (USDOC), Census Bureau. 2015. 2012 Commodity Flow Survey, Hazardous Materials (Washington, DC: February 2015). Available at http://www. census.gov/ as of May 2015.

U.S. Department of Transportation (USDOT), Bureau of Transportation Statistics (BTS), and USDOT, Federal Highway Administration (FHWA), Office of Freight Management and Operations. Freight Analysis Framework, version 4, 2016.

U.S. Department of Transportation (USDOT), Bureau of Transportation Statistics (BTS):

—2016a. BTS Press Release 41-16: June 2016 Freight Transportation Services Index (August 10). Available at http://www.bts.gov/ as of August 2016.

—2016b. BTS Press Release 17-16: 2015

 North American Freight Numbers (March 18). Available at http://www.bts.gov/ as of March 2016.

—2016c. TranStats, Air Cargo Summary Data. Available at http://www.transtats.bts.gov/ as of April 2016.

—2016d. Pocket Guide to Transportation (January 2016). Available at http://www.bts. gov/ as of April 2016.

Chambers, M. Containerships Carry Inventory for U.S. Retailers (2012). Available at http:// www.bts.gov as of August 2016.

U.S. Department of Transportation (USDOT), Federal Aviation Administration (FAA). CY 2014 Passenger Boarding and All-Cargo Data. Available at http://www.faa.gov/ as of April 2016.

U.S. Department of Transportation (USDOT), Maritime Administration (MARAD):

—2016a. 2015 Vessel Calls in U.S. Ports, Selected Terminals and Lightering Areas (June). Available at http://www.marad.dot.gov/ as of August 2016.

--2016b. MARAD Open Data Portal, Maritime Data & Statistics. Available at http://www. marad.dot.gov as of August 2016.

—2013. Panama Canal Expansion Study (November 2013). Available at http://www. marad.dot.gov/ as of April 2016.

—U.S. Geological Survey (USGS). 2016. Water Quality Topics: Hydraulic Fracturing. Available at http://water.usgs.gov as of May 2016.

¹ Many shipments moving by rail or water are transferred to another mode for delivery to their final destination. In FAF, these shipments are counted under “multiple modes and mail.” Thus the rail and water numbers discussed here may differ from those in other published sources.

² In all service classes (scheduled and nonscheduled).

³ The FAF category for multiple modes and mail in- cludes all multimodal movements and is not limited to traditional intermodal services, such as trailer-on-flatcar and container-on-flatcar rail.

⁴ Coke is a solid fuel usually made by heating coal in the absence of air. It has high carbon content and is used primarily as a fuel in smelting iron ore in a blast furnace.

⁵ A vessel advertising sailings on a specified trade route on a regular basis. It is not necessary that every named port be called on every voyage.

⁶ The percent increase was calculated by adjusting the 2000 trade data using the CPI Inflation Calculator.