The U.S. transportation system carried 18 percent more tons of freight in 2002 than in 1993 . This growth was unevenly distributed in terms of geography and by mode, in part because of the differing characteristics of truck, waterborne, and rail modes and the infrastructure on which each relies.
At more than 120 million tons, waterborne freight flows in 19981 were heaviest along the Mississippi River, while between 70 million and 120 million tons flowed along the Ohio and Illinois Rivers and within the Great Lakes (figure 2-12). Lesser amounts were transported north and south along various rivers connected by the Tennessee Tombigbee Waterway.
Some of the heaviest truck flows in 1998 (those greater than 120 million tons) occurred along routes in California and Texas; around Atlanta, Georgia; and within the central and northeastern areas of the country (figure 2-13).
Main rail routes carried more than 20 million tons of freight in 1999 throughout the United States (figure 2-14).
Intermodal flows, in which a combination of modes are used to transport freight, are becoming increasingly important. In the regional Lake Michigan area, for instance, maritime and trucking provide intermodal services not only at lake ports but inland as well (figure 2-15).
These mapped data were generated by GeoFreight . This analysis tool was developed in 2003 by the Bureau of Transportation Statistics, the Federal Highway Administration, and the Office of Intermodalism of the U.S. Department of Transportation to help freight policymakers and planners identify flows of domestic and international freight across the country and assess major freight bottlenecks in the transportation system. Geographic displays produced using GeoFreight enable comparisons of infrastructure impacts by mode at national, regional, and local levels.
1. U.S. Department of Transportation, Bureau of Transportation Statistics, Federal Highway Administration, and Office of Intermodalism (Office of the Secretary), GeoFreight, CD (Washington, DC: 2003).
2. U.S. Department of Transportation, Bureau of Transportation Statistics and U.S. Department of Commerce, U.S. Census Bureau, 2002 Economic Census, Transportation, 2002 Commodity Flow Survey (Washington, DC: 2003), preliminary data.
1 The most recent data available when this report was prepared was 1998 for trucking and waterborne and 1999 for rail.