The increased use of oceanborne containers in transporting U.S. international trade continues to affect port operations and the distribution of total maritime trade among U.S. ports. Before the mid-1980s, east coast ports handled the majority of U.S. international maritime trade. As U.S. trade with Asia-Pacific countries grew, the east coast ports' share of international maritime trade declined and west coast ports' share increased (figure 12). In 1986, west coast ports surpassed east coast ports in maritime cargo handled. This trend has continued, although the gap between the two regions has narrowed.
As measured in TEUs, over half of U.S. containerized merchandise trade passes through west coast ports. In 2009, 51 percent of U.S. containerized imports and exports passed through these ports, down slightly from 56 percent in 2006 (figure 12). West coast ports as a region grew the fastest beginning in the mid-1980s, but they suffered the sharpest decline in container traffic since 2007 (figure 13). Between 2007 and 2009, total TEUs handled by west coast ports declined 22 percent, compared with 13 percent decline for east coast ports and less than 1 percent increase for gulf coast ports.
West coast ports handle the most container trade today, but they have also had a larger share of the oceanborne containerized trade deficit since 2007 than ports in other regions. Today, west coast ports serve more as import gateways to the United States than as export gateways while east coast ports handle more exports than imports, despite the decline in the east coast's regional market share.
Since 1980, changes in industrial activity in the Midwest United States have affected the volume and type of cargo moving through Great Lakes ports. For example, the relocation of automobile final-assembly plants and companies that produce auto parts had an impact on manufacturing activities in the Midwest. With the emergence of automakers and parts producers in other locations of the United States, maritime cargo originating in the Midwest and cargo transport via the Great Lakes dwindled. In 2008, according to the U.S. Army Corps of Engineers, Great Lakes ports handled nearly 3 million short tons of maritime exports and imports, compared with about 10 million short tons in 1980. They handled 1 million short tons of exports in 2008, down from 8 million in 1980 (USACE NDC 2008). The volume of containerized cargo handled by Gulf of Mexico ports more than quadrupled during this period, although their relative share remained steady as volume at west coast ports rose.
Changes in container trade also affect the pattern of freight movement within the United States. For example, some east coast ports are expecting an increase in their container traffic after completion of the Panama Canal expansion that is currently underway. Additional traffic through these ports will increase cargo movements on east coast rail and truck freight corridors. Some ports use marine highways as an alternative to transport goods shorter distances.12 The growth in U.S. containerized cargo shipping places pressure on the Nation's transportation network, affecting local traffic congestion and contributing to traffic delays in urban areas surrounding the major U.S. container ports. (See Spotlight 1 on landside access to the seaports.)
12 The term "marine highway" refers to coastal waterways that are used to move freight (e.g., from Long Beach to Portland or from New York/New Jersey to Savannah). It includes the movement of containers and wet and dry bulk cargoes.