Box D - Freight Transportation Intensity of the U.S. Economy
There is a close link between growth in freight transportation and economic growth. Changes in economic activities influence the demand for freight services. An indicator, known as freight transportation intensity, illustrates this relationship. Measured as the ratio of total ton-miles to total GDP, this indicator shows that the actual freight activity required to produce a unit of goods and services in the nation's GDP has declined. The ratio dropped from 0.59 ton-miles per dollar of GDP in 1970 to 0.38 ton-miles per dollar of GDP in 2002 (as measured in 2000 dollars). This suggests an increase in freight transportation productivity. Alternatively, this decline may be due to GDP growing at a faster rate than growth in freight transportation. Changes to the ratio reflect both macro level driving forces (e.g., the shift in the structure of the economy from goods to more services) and micro level factors (e.g., changes in freight rates, time in transit, accessibility to ports, and security of goods).
SOURCE: Bureau of Transportation Statistics, February 2004.