Introduction and Overview

Introduction and Overview

America's freight transportation gateways-seaports, airports, and land border crossings-are vital for U.S. economic growth and international competitiveness. They are the entry and exit points for merchandise trade between the United States and countries around the world. The gateways and the accompanying shipping, railroad, highway, and aviation systems link the U.S. population, economic sectors, and businesses to the global marketplace. Each year, U.S. businesses, farms, manufacturers, and households depend on these transportation facilities to move large quantities of goods. When freight gateways do not work well-because of delays, traffic congestion, or service problems-the timely flow of goods can be impeded, causing economic loss to shippers, carriers, and households. When gateways work well, however, U.S. businesses thrive and trade with partners around the world, and American households enjoy access to a wide variety of imported goods.

America's Freight Transportation Gateways 2009 is an update of a report released in 2004 by the Bureau of Transportation Statistics of the Research and Innovative Technology Administration. This current report is a data profile of the nation's leading international freight transportation gateways in 2008 and presents summary trend data from 1990. It is a collection of information that highlights the top 25 freight gateways, providing the most recent annual information on the movement of goods through these seaports, airports, and land border crossings (box 1). Additional information on more than 200 gateways that are key points of entry and exit for U.S. international trade is available on the BTS website at

In July 2009, about $221 billion of international merchandise passed through more than 400 U.S. seaports, airports, and land border crossings that collectively comprise America's freight gateways. This was down 30 percent from $317 billion in July of 2008. From January through July 2009, more than $1.4 trillion worth of goods moved through these transportation facilities, down 29 percent compared to $2 trillion for the same period in 2008 (USDOC CB 2009a). These declines started in mid-2008 and continued through early 2009.

However, U.S. freight gateways handled more than $3.4 trillion (in current dollars) of international merchandise trade in 2008, an increase of 9 percent from 2007 (table 1). Merchandise exports rose by 12 percent and imports by 7 percent. Since 1990, the leading U.S. freight gateways have handled increasing volumes of freight as the movement of traded goods to and from the United States expanded.

From 1990 to 2008, the value of U.S. international merchandise trade grew from $889 billion to $3.4 trillion, increasing at an average annual rate of 8 percent per year. In inflation-adjusted terms (using chained 2000 dollars), this trade grew about 7 percent per year, from $837 billion to more than $2.7 trillion (table 1). During the 1990 to 2008 period, the growth in merchandise trade spurred the development of marine, air cargo, and border crossings facilities to connect domestic U.S. origins and destinations to markets abroad.

While more than 400 U.S. seaports, airports, and land border crossings handle international merchandise trade, most of the trade passes through relatively few gateways. In 2008:

  • the nation's top five freight transportation gateways handled 25 percent ($865 billion) of the total value of U.S. international merchandise trade,
  • the top 16 gateways handled 50 percent ($1.7 trillion) of U.S. international merchandise trade, and
  • the top 50 gateways handled 78 percent ($2.7 trillion) of the value of that trade (table 2).1

During the past two decades, the demand for freight transportation services in the United States increased and changed as the freight gateways handled increasing volumes of merchandise trade. New and complex approaches for managing inventory and logistics supply chains as well as changes in trading partners drove demand for freight transportation to record levels. Exports continued to account for an increasing share of U.S. gross domestic product (GDP), and imports of manufactured and consumer goods gained an increasing share of U.S. markets (figure 1). During this period, the relative importance of international merchandise trade to the overall U.S. economy increased. In inflation-adjusted terms, the ratio of goods traded in comparison to GDP rose significantly-it stood at 23 percent in 2008, up from 12 percent in 1990.

The large volume of U.S. traded goods must, by necessity, pass through freight gateways as they are transported by ocean vessels, railcars, airplanes, and trucks from origins to destinations. During the past two decades, the gateways have faced increased demand for improved cargo-handling services as businesses streamlined production and distribution processes through such measures as carrying smaller inventories and ordering raw materials and parts to arrive just-in-time. To keep pace and remain competitive, the gateways had to provide faster, more efficient, and more reliable services for freight transported between U.S. and world markets. The gateways have also faced increased environmental, capacity, and infrastructure concerns-unintended consequences of the growth in the freight they handle. Reducing environmental impact,

resolving congestion and accessibility challenges, and managing the physical infrastructure remain daunting tasks for freight gateways. The spotlights beginning on page 17 provide examples of these issues at the Port of Los Angeles, John F. Kennedy (JFK) International Airport in New York, and the Detroit land border crossing.

The Nation's Busiest Freight Transportation Gateways

With merchandise trade growing during the last two decades, gateways have become more vital for U.S. economic activity, opening new opportunities for U.S. businesses to trade with global markets. Figure 2 shows a map of the nation's top 25 ports of exit and entry, by value, for U.S. international trade shipments in 2008. This map illustrates the geographic pattern of freight activity at the leading gateways and the multimodal nature of the nation's freight transportation system.

A list of the top five gateways includes all three transportation modes-water, air, and land:

  • The Port of Los Angeles was the leading gateway overall for international trade, with more than $244 billion in oceanborne cargo.
  • The Port of New York and New Jersey ranked second in value, handling $185 billion in oceanborne cargo.
  • New York's JFK International Airport ranked third in value, with $168 billion of air cargo.
  • The Port of Houston ranked fourth in value, with $148 billion in oceanborne trade.
  • The land border crossing of Detroit ranked fifth, with a total of $120 billion in surface freight.

Many factors determine the size and direction of freight shipments handled by the gateways, including changes in commodities traded internationally between the United States and its trading partners, changes in major U.S. trading partners, changes in the global economy, and geographic shifts in centers of production worldwide.

Table 2 shows that the top 50 freight gateways in 2008, ranked by value of total trade, are located in 20 states, the District of Columbia, Puerto Rico, and the Virgin Islands. While U.S. freight gateways typically handle both exports and imports, some serve primarily as gateways for imports into the United States, and others serve more as gateways for exports from the United States to markets around the world. For example, exports accounted for just about 14 percent of the value of cargo handled by the top freight gateway, the maritime Port of Los Angeles. Meanwhile, two of the top five gateways, the land border crossing of Detroit and JFK International Airport, handled more exports than imports in terms of value (table 2). The proportion of U.S. international freight that is imported changes in response to shifts in U.S. trade relationships. The rising importance of U.S. trade with Mexico and China underscores the growth of freight imports passing through the land border gateways (e.g., Laredo, TX) and west coast ports (e.g., Ports of Los Angeles and Long Beach).2

During the 1990s, JFK International Airport was the leading gateway for overall merchandise trade by total value of shipments, but by 2003, the Port of Los Angeles had risen to the number one position. Since 2003, the Port of Los Angeles has maintained the leading position, and the value of maritime trade passing through the port's facilities doubled. From 2003 to 2008, imports at the Port of Los Angeles jumped 99 percent in value, while exports grew 107 percent-an overall growth of 100 percent, far above the 62 percent average growth for the top 25 gateways (table 3). This growth reflects a major increase in trade with Pacific Rim Asian countries, especially growth in merchandise trade from China. During this period, the maritime Port of New York and New Jersey moved from fourth to second place, reflecting strong growth in containerized trade with Europe. And the seaport of Houston jumped from 11th to 4th place, indicating a sharp rise in maritime cargo trade with South America, particularly bulk commodities and crude petroleum.

Modal Shares by Value and Weight

The relative roles of transportation modes in carrying the large volume of U.S. international merchandise trade vary by value and weight. Waterborne vessels account for more U.S. international trade, both in terms of tonnage and value, than any other mode: 78 percent of the weight and 45 percent of the value of U.S. merchandise trade in 2007 (figure 3).3 Water transportation is less dominant in terms of value because higher-value-per-ton commodities often move by air and truck, particularly in U.S. trade with Canada and Mexico.
Freight moving through land gateways accounted for 22 percent of the weight of overall U.S. trade but 24 percent of the value. Of these, trucks accounted for 10 percent of the weight and 18 percent of the value (USDOT RITA BTS 2009a).

Air cargo accounted for 25 percent of the value of total U.S. merchandise trade in 2007, but its share of the weight remained less than 1 percent.

Modes vary in the proportion of imports and exports they carry. While water transportation accounted for 79 percent of U.S. import tonnage and 76 percent of U.S. export tonnage in 2007, its share of the value of all U.S. imports was 52 percent, and its share of all exports was 32 percent. By contrast, trucks moved 15 percent of the value of all imports and 23 percent of the value of all exports (USDOT RITA BTS 2009a).

Differences in the modal shares of U.S. international trade directly affect the movement and flow of freight traffic on transportation networks of the United States. They also affect the demand for vehicle inspections at U.S. ports and border crossings. In addition, they influence the need for improved security for the millions of truck trailers and containers that enter the United States.

Land Freight Gateways

In 2008, U.S. merchandise trade with North American Free Trade Agreement (NAFTA) partners Canada and Mexico totaled $964 billion, more than one-fourth (28 percent) of the value of overall U.S. merchandise trade (table 4). As trade with Asia has expanded, this share has declined from the record high of 33 percent in 2001.

Canada, Mexico, and the United States are all participants in NAFTA, which was put in place by the three countries in 1994 to reduce trade barriers and liberalize trade policies. For convenience, this report refers to U.S. trade with Canada and Mexico as U.S.-NAFTA trade.

Land trade-carried by truck, rail, and pipeline-accounted for 86 percent of the value of U.S.-NAFTA trade, or $830 billion, in 2008.4

The magnitude of U.S.-NAFTA land trade highlights the importance of north-south freight transportation corridors and the role of key land gateways. It underscores the dominant freight corridors (e.g., between Detroit, Michigan, and Laredo, Texas), which will continue to affect the pattern of domestic freight movements within the United States (USDOT RITA BTS 2003).

Since 1990, the value of U.S. land trade with Canada and Mexico has grown at an average annual rate of 8.1 percent per year, a slightly faster pace than the 7.7 percent for overall U.S. trade with all countries (table 5). As a result of this growth, land trade's share of the value of total U.S. merchandise trade grew slightly from 23 percent in 1990 to 24 percent in 2008 (figure 4).5

While there are 75 land border crossings along the U.S.-Canadian border and 25 along the U.S.-Mexican border, the land freight transported across the northern and southern borders is heavily concentrated at a few major gateways. This concentration affects traffic and congestion at the borders as well as the growth of major freight transportation corridors. In 2008, the top three ports for U.S.-NAFTA land trade by value were Detroit, Michigan; Laredo, Texas; and Port Huron, Michigan. In total, these three ports accounted for more than 38 percent of the value of all U.S.-NAFTA land trade in 2008.

Besides serving local markets, most of the top U.S. land border ports are national and multistate regional trade gateways. The proportions vary considerably among gateways. Only about 36 percent of freight shipments (by value) passing through Detroit originate or terminate in Michigan. For Laredo, the biggest U.S.-Mexican border port, only 28 percent of shipments start or end within Texas. By comparison, 88 percent of shipments passing through Otay Mesa, the largest California port on the U.S.-Mexican border, originate or terminate in that state.

In value terms, trucks carried more than two-thirds (67 percent) of all U.S. land trade, worth about $554 billion, in 2008. This share was down about 3 percentage points from 2007. Rail transborder freight's share remained steady at about 17 percent, valued at $140 billion, in 2008. Pipelines carried $88 billion of products, a 48 percent jump from 2007, primarily resulting from a rise in the value of U.S. imports of petroleum products from Canada. The share for pipelines was 11 percent in 2008, up 4 percentage points from 2007 (USDOT RITA BTS 2009b).

Although trucks haul the majority of U.S. trade by value at the major land border crossings, many crossings are important rail gateways, facilitating the transport of long-haul freight to and from origins and destinations in several states. Rail plays an important role in particular freight corridors and for certain commodities in U.S.-NAFTA trade. About half of the value of U.S.-NAFTA rail trade passes through just three land gateways: Port Huron, Michigan; Laredo, Texas; and Detroit, Michigan. In 2008, the leading rail gateway, Port Huron, handled $27 billion of freight, down 9 percent from 2007. Laredo and Detroit experienced 6 and 16 percent drops in the value of rail freight, respectively (USDOT RITA BTS 2009b).

By weight, land modes hauled more than 269 million short tons of imported goods entering the United States from Canada and Mexico in 2008, down 4 percent from 2007 (table 6). The tonnage of land imports from Canada fell 4 percent, while tonnage from Mexico fell about 5 percent.6 Regarding modal shares, in 2008 trucks moved 33 percent of the tonnage of total land trade imports, rail moved 32 percent, and pipelines accounted for 35 percent (figure 5). Trucks transported a larger percentage of the tonnage of U.S. land imports from Mexico (74 percent) than from Canada (25 percent). By comparison, in 2008, rail transported 24 percent of the tonnage of land imports from Mexico and 33 percent from Canada (table 6).

Vehicle Crossings at Land Gateways

Each day, large numbers of motor vehicles and rail equipment carrying imported goods enter the United States. In 2008, there were 10.8 million commercial truck crossings into the United States from Canada and Mexico, down 6 percent from the 11.4 million crossings in 2007 (table 7).7 Commercial trucks entering the United States at the busiest land gateways-Detroit, Michigan, and Laredo, Texas-generate heavy north-south truck traffic along the corridor that links these border crossings. These commercial trucks entering the United States carried 7.7 million full containers and 2.9 million empty containers in 2008.

The land gateways also handled about 40,000 trains carrying about 2.7 million containers headed for the United States from Canada and Mexico in 2008 (approximately 110 trains and 7,400 containers per day). Nearly 30,000 of these trains entered from Canada. From 2000 to 2008, the number of rail containers entering the United States grew faster (24 percent) than the number of incoming truck containers (2 percent). Most of the growth was in incoming rail containers from Canada, because U.S. rail freight with Canada is larger than U.S. rail freight with Mexico (table 7).

From 2000 to 2008, the number of truck crossings into the United States from Mexico grew by 8 percent, but truck crossings from Canada declined by 16 percent. The growth in inbound truck crossings from Mexico occurred despite the fact that the United States has delayed the full implementation of the NAFTA trucking provision that allows Mexican trucks to travel into the interior of the United States.8

Water Freight Gateways

In 2008, nearly three-quarters (72 percent) of the value of U.S. international merchandise trade passing through U.S. freight gateways was to and from countries other than Canada and Mexico and was worth about $2.4 trillion (table 4). Maritime trade accounted for about 63 percent ($1.5 trillion) of this trade; air freight accounted for the rest (USDOC CB 2009b). Since 1990, the value of total U.S. overseas trade has nearly quadrupled, rising at an average annual rate of 8 percent per year (table 4).9

Maritime trade passing through U.S. seaports rose from $434 billion in 1990 to $1.6 trillion in 2008, about an 8 percent annual rate (table 5). This growth was spurred by the rising importance of China as a trading partner even though the maritime cargo growth rate was slightly outpaced by growth in U.S.-NAFTA surface trade and U.S. air trade.10 The growth also underscores the continued expansion of trade with several Pacific Rim Asian nations and the dominance of the Port of Los Angeles as the nation's top freight gateway by value in 2008. While oceanborne cargo passing through U.S. seaports in 2008 accounted for the largest modal share (48 percent) of the value of overall U.S. merchandise trade, this share has fallen slightly from 49 percent in 1990 as the shares for land trade and air trade have increased slightly (figure 4).

The prominence of the Port of Los Angeles as a top gateway by value of goods reflects the specialization among U.S. seaports. The Pacific and Atlantic coast ports are heavily involved in the container trade, while the U.S. gulf coast ports are primarily involved in the dry bulk and tanker trade. Gulf ports such as Houston, Texas, lead other U.S. ports in terms of tonnage of international cargo shipments. These shipments are primarily petroleum, agricultural goods, coal, and other bulk commodities. In general, bulk commodities are lower value per ton, and containerized commodities are higher value per ton.

More than 1.5 billion short tons of international maritime cargo were transported through U.S. seaports in 2008. Exports accounted for 35 CB 2009b). About 15 percent, or 232 million short tons, of this maritime cargo involved U.S.-NAFTA trade, and the remaining 85 percent resulted from overseas trade. U.S.-NAFTA maritime trade accounted for 13 percent of the weight of total maritime exports and 17 percent of the weight of imports.

Table 8 shows that the order of the largest seaports changes when the seaports are ranked by tonnage rather than by cargo value. In 2008, the top three seaports by weight were the Port of Houston (more than 150 million short tons of freight), the Port of New Orleans (98 million tons), and the Port of New York and New Jersey (90 million tons). The top 20 seaports accounted for 64 percent of the maritime export tonnage and 71 percent of the import tonnage.

The difference between the rankings of the top maritime ports by value and by tonnage reflects variation in the types of goods being imported and exported, which affects the kinds of vessels and seaports used. The weight and value of commodities are among the factors that determine the use of tanker, bulk, or container vessels. Among the leading seaports in 2008, for example, Houston, the top port by weight, handled more than 150 million short tons worth $148 billion-about $980 per ton. By comparison, Los Angeles, the top port by value, handled more than 75 million short tons worth $244 billion-about $3,200 per ton. Low-value-per-ton commodities (e.g., petroleum, agricultural, and lumber products) move by bulk and tanker vessels, while higher value merchandise (e.g., electronics, vehicle parts, and other manufactured products) move by container vessels.

Air Freight Gateways

In 2008, air freight accounted for 24 percent ($806 billion) of the total U.S. merchandise trade of $3.4 trillion (figure 4). From 1990 to 2008, the value of inbound and outbound air cargo handled at the U.S. gateway airports grew at an average annual rate of about 8 percent (table 5).

U.S. air trade with Canada and Mexico in 2008 accounted for about 5 percent ($41 billion) of the value of the total U.S. merchandise trade transported by air, because the majority of U.S.-NAFTA trade moves by land modes. Overall, U.S. air cargo exports represented 48 percent ($388 billion) of the total air trade. In comparison, maritime exports represented 29 percent ($472 billion) of the total oceanborne trade (USDOC CB 2009b).

John F. Kennedy International Airport in New York was the leading U.S. airport for international freight by value in 2008, handling about one-fifth (21 percent) of U.S. air imports and exports, valued at $168 billion. Before 2003, JFK International Airport was the leading gateway of any type by value. Because of a large increase in U.S.-Asia trade, it was overtaken in 2003 by the maritime Port of Los Angeles.

In 2008, U.S. air gateways handled nearly 8 million short tons of international air freight-47 percent outbound as exports and 53 percent inbound as imports (USDOC CB 2009b). Valued at more than $806 billion, this higher-value-per-ton freight averaged more than $102,000 per ton. JFK International Airport handled merchandise valued at about $130,000 per ton. Because the goods transported by air carriers tend to be higher in value per ton (e.g., electronics, clothing, and high-value perishables such as cut flowers) than those carried by other modes, air freight's share of U.S. trade by weight remained less than 1 percent. Because air cargo is mostly higher value merchandise, the value of shipments is a more representative indicator of the importance of air gateways to the nation's international commerce.

By weight, Ted Stevens Anchorage International Airport was the nation's leading air gateway, handling about 2.5 million short tons, more than one-quarter of the total international air freight tonnage in 2008 (table 9).11 Miami International Airport and New York's JFK followed, handling more than 1.7 million short tons and 908,000 short tons, respectively.
U.S. international air cargo originating from and destined for U.S. freight gateways are transported along major air routes, or air segment pairs between major markets (see box 2). Measured by weight, 5 of the top 10 gateway pairs for imports and 4 of the top 10 gateway pairs for exports in 2008 included Ted Stevens Anchorage International Airport. The pairing of Anchorage-Seoul ranked first in bidirectional international air cargo, handling more than 650,000 short tons of freight (table 10).

The airport pairs show regional specialization among major U.S. air gateways. All nine foreign airports paired with Anchorage were in Asian Pacific countries: South Korea, Japan, Hong Kong, China, and Taiwan.12 Los Angeles International Airport was also part of a top gateway pair with an Asian Pacific airport. New York's John F. Kennedy International Airport and Chicago's O'Hare International Airport were the major gateways to airports in the United Kingdom, Belgium, and Germany. Miami International Airport's top gateway pairs were with airports in Brazil, Colombia, Ecuador, Peru, and Chile (USDOT RITA BTS OAI 2009).

Gateways and Data Needs

The lack of complete data on U.S. international freight hampers research and analysis of trends in international freight movement and its impact on transportation activity within the United States. No single data source provides all the data needed for international transportation research (see box 3). Fully understanding trends in the movement of goods and having reliable forecasts for transportation decision making require consistent and comparable data on both the weight and the value of internationally traded goods. The lack of weight data for land exports remains a problem for transportation freight analysis. The U.S. Census Bureau, the U.S. agency in charge of reporting U.S. merchandise trade data, does not collect shipment weight data for exports transported by truck, rail, and pipeline.

Another data gap for international freight transportation analysis is the lack of comprehensive outbound border-crossing information from official U.S. government sources. Data are only collected for incoming trucks and trains as well as the containers they carry. This data gap continues to limit analysis of transportation activity at the land border gateways, including such issues as capacity needs, congestion management, traffic delays, and safety.

Spotlights on Select Challenges

Water Gateways Tackle Environmental Concerns: Los Angeles and Long Beach

As society has gained heightened awareness about the environment, maritime gateways have focused considerable effort on how they can best manage their environmental impact. For example, the Port of Los Angeles-now the top maritime gateway by value-and the Port of Long Beach, in partnership with the U.S. Environmental Protection Agency (EPA) and other agencies, adopted the San Pedro Bay Ports Clean Air Action Plan in 2006. It seeks to curb port-related air pollution from trucks, ships, locomotives, and other equipment by at least 45 percent in 5 years. The ports are also engaged in a coordinated plan that targets sources of water and sediment pollution in San Pedro Bay.

The Clean Truck Program at the Port of Los Angeles provides financial incentives to trucking companies to purchase vehicles powered by natural gas or lithium battery electric power. The Los Angeles Harbor Commission approved up to $44.2 million for the program in 2009, following a 2008 program that put into service more than 2,200 trucks that met or exceeded 2007 EPA emission standards. The port hopes to put 1,000 alternative fuel trucks into service by the end of 2009. In the first 6 months of the Clean Truck Program, truck pollution at the Los Angeles-Long Beach port complex was reduced by more than 23 percent (Port of Los Angeles 2009).

Among other initiatives, the Port of Los Angeles approved funding in 2007 for developing a new hybrid tugboat that blends battery power with diesel generators. The first hybrid tug debuted in 2009. The hybrid design is projected to cut emissions by 44 percent and fuel consumption by up to 30 percent (EPA 2008). Traditional tugboats can also be retrofitted with the hybrid technology to make them more energy efficient. In 2009, the Port of Los Angeles, along with the Port of Long Beach, funded an "eco-tug" demonstration project that will retrofit existing engines on a harbor tugboat with new technology to reduce emissions. Port funds are also going toward a prototype all-electric truck for use in the marine terminal and in port drayage service. In addition, as part of a capital improvement program, the Port of Los Angeles is using sustainable practices in the redevelopment of container terminals and transportation infrastructure.

The Port of Long Beach's Clean Trucks Program, which started October 1, 2008, aims to cut by 2012 air pollution from the thousands of trucks that haul cargo containers to and from the port's terminals. The key component of the port's program is a ban to phase out the oldest, highest-polluting trucks in favor of trucks that meet 2007 federal emission standards. Long Beach's program started with a ban on 1988 and older trucks. On January 1, 2010, 1993 and older trucks will be banned, as well as 1994 to 2003 trucks that are not retrofitted to reduce air pollution. Motor carriers must equip their port trucks model year 1994 to 2003 with a California Air Resources Board verified emission control device to gain access into the port's container terminals. As of mid-September, 2009 the Port of Long Beach reports that nearly 5,000 clean large trucks are moving more than half of the truck-hauled cargo at the port (Port of Long Beach 2009).

Air Gateways Handle Growth and Capacity Issues: JFK International Airport

John F. Kennedy International Airport is America's top international air cargo gateway. In 2008, more than 21 percent of U.S. international air cargo by value passed through it. Effectively managing such a large amount of air freight while continuing to maintain and upgrade the infrastructure is a key challenge. JFK's infrastructure includes 9 miles of runways, 25 miles of taxiways, more than 30 miles of roadways, and an air cargo area covering 1,700 acres (Port Authority of New York and New Jersey 2009b, 2009c).

Between 2003 and 2008, international air cargo handled at JFK grew 50 percent, from $112 billion to $168 billion. Exports grew 84 percent, and imports grew 26 percent. In 2008, the airport moved an average of nearly $460 million in merchandise cargo each day, carried by airlines from more than 50 countries. The top commodities transported through JFK are high-value products, such as pearls and precious stones, electronic equipment and machinery, and precision instruments. Additionally, scheduled passenger flights at JFK grew 71 percent, from 119,700 in 2003 to 204,650 in 2008, creating even more pressure to maintain the infrastructure.

JFK's ability to handle growing cargo as well as passenger demand is based primarily on its airfield capacity-the number and placement of runways and taxiways, types of navigational aids, and types of air traffic control and facilities. Other factors, such as airline scheduling, aircraft performance, mix of aircraft types, weather, and runway closures, affect how much of the airport's capacity can be used at a given time. Such variability in capacity can result in airport congestion and eventually air traffic delays. On a typical day, when demand approaches or exceeds capacity for extended periods of time, any disruption can create persistent delays.

While there are no plans for constructing additional runways to increase the physical airfield capacity, JFK plans to improve operational efficiency for both good and adverse weather capacity by changing arrival and departure procedures, deploying advanced technology, and restructuring airspace to provide more efficient air routes. Moreover, in June 2009, the Port Authority of New York and New Jersey accepted a grant under the American Recovery and Reinvestment Act of 2009 to help fund a runway rehabilitation and widening project at JFK (Port Authority of New York and New Jersey 2009a).

JFK has 4 million square feet of warehouse and office space for cargo operations. In recent years, more than $375 million has been invested in new cargo facilities. Plans to redevelop two older cargo facilities would add about 600,000 square feet of new cargo space (Port Authority of New York and New Jersey 2009b).

Land Gateways Manage Complex Issues: Detroit

The busiest land transportation gateway in the United States-and fifth-largest gateway overall-is Detroit, Michigan. In 2008, merchandise trade passing through Detroit was valued at $120 billion, or 15 percent of the value of U.S. total land trade. While some goods move through Detroit by rail, most freight travels through this gateway via truck. Three major transportation pathways connect Detroit and Windsor, Ontario: the Ambassador Bridge, the Detroit-Windsor Tunnel, and rail tunnels. There is also a truck ferry. The Ambassador Bridge currently carries most of Detroit's truck traffic.

The confluence of transportation issues presented at the Detroit gateway underscores the complexity that characterizes the flow of land trade today. By virtue of its geographic location and the sheer volume of freight it handles, Detroit is important in the context of U.S.-NAFTA trade and border security. The heavy-and growing-flow of goods highlights three other critical concerns: congestion, infrastructure management, and environmental impact.

These complex issues are at play in recent efforts to improve cross-border transportation at the Detroit gateway. A binational planning and feasibility study completed in 2004 projected a need for additional roadway capacity on both sides of the border and an additional river crossing over the next two decades (Canada-U.S.-Ontario-Michigan Border Transportation Partnership 2004). To accommodate more truck traffic, the private owner of the Ambassador Bridge has plans to build a parallel span but has yet to secure needed permissions. Meanwhile, national, state, and provincial agencies from the United States and Canada plan a separate new bridge that would also link Detroit and Windsor.

The potential new bridge projects have led to discussions about their environmental impact, their effect on communities that would be encroached on by new roadways, and the traffic congestion that new routes might create. These and related concerns point to the intricate network of issues to be addressed to ensure efficient and safe movement of freight at the land gateways.

1 This report uses the value of traded goods rather than the weight of traded goods to rank the leading freight gateways, because weight data for land exports are not collected by U.S. authorities (see box 1). Hence, this report does not cite weight data for land exports at individual gateways. However, BTS has estimated the weight of land exports at the national level based on value-to-weight ratios from the import data, and this information is presented in figure 3. Additional information on U.S. trade data is also presented in box 3..

2 In 2008, China and Mexico were the second and third largest U.S. trading partners respectively, after Canada. However, in 1970, Mexico was the fifth ranked U.S. trading partner. By 1990, Mexico had climbed to the third position, and by 2001, it had moved past Japan to become the second largest trading partner. In 1970, China was not listed separately in U.S. official trade statistics; it was listed as part of the "Communist World." By 1990, China was the 10th leading trading partner and rose to the second position in 2006 (based on U.S. Department of Commerce, U.S. Census Bureau, Statistical Abstract of the United States, various years).

3 2007 is the most recent year for which tonnage data are available for the land modes of transportation. These tonnage data are necessary to allow modal comparison by weight.

4 Maritime vessels accounted for about 8 percent and air cargo for 6 percent.

5 Official figures are unavailable by tonnage because weight data for surface exports are not collected by U.S. authorities.

6 As mentioned in box 1, weight data for land modes are only available for imports. BTS has estimated the weight of land exports at the national level by using value-to-weight ratios from import data.

7 These figures represent the number of incoming crossings, not the number of unique individual vehicles. They include both loaded and unloaded commercial trucks. For example, if a truck crosses the border multiple times in one day, each incoming crossing is counted. Official data for outgoing trucks, trains, and containers at all land border crossings are not collected by U.S. government agencies.

8 Canadian carriers are permitted to operate anywhere in the United States provided they comply with U.S. regulations and carry only international cargo. U.S. carriers have reciprocal access in Canada. Currently, Mexican carriers can only service the commercial zones along the U.S. southern border and need special operating authority to service places outside this border zone.

9 For comparison purposes, U.S.-NAFTA maritime and air trade are excluded from these statistics. In 2008, U.S. maritime trade with Canada and Mexico was $93 billion; U.S. air trade was $41 billion.

10 Canada remains the top overall partner for total imports and exports, followed by China and Mexico.

11 The airport gateway tonnage figures are from the Bureau of Transportation Statistics' Office of Airline Information and reflect carrier data reported by both U.S. and foreign carriers. The data also include transshipment cargo carried by carriers that stop at connecting airports to refuel. For Anchorage, which is a large connecting hub, this means some of its foreign cargo simply passes through the airport to non-U.S. destinations and are not counted as part of official U.S. trade statistics. Therefore, these data are not directly comparable to shipper-based merchandise trade data for international air activity from the U.S. Census Bureau. This explains why JFK was top in value and Anchorage top in weight.

12 For official merchandise trade statistics, the U.S. Census Bureau reports Hong Kong and Taiwan separately. In this report, China refers to mainland China.