|Value (billion $)||Tons (millions)||Value (billion $)||Tons (millions)|
1 2001 value and weight for exports and imports are official U.S. trade statistics. The value for 2001 domestic shipments is a projection from the 1997 Commodity Flow Suvey (CFS) data, based on the annual average growth rate of current U.S. gross domestic product (GDP) (5.2%) between 1997 and 2001. The tonnage for 2001 domestic shipments is a projection from 1997 CFS data, based on the annual average growth rate of domestic freight movements (3.4%) between 1993-1997, adjusted for the variation in GDP growth rate between 1993-1997 (5.8%) and 1997-2001 (5.2%). The 2001 projections are subject to uncertainties, because they assume freight grew at an annual rate similar to GDP. Also, because the CFS is a survey, the data are subject to sampling and nonsampling errors.
NOTES: The 1997 domestic figures are estimates based on the CFS minus export shipments. CFS data published in other BTS publications include exports.
SOURCES: Domestic data-U.S. Department of Transportation (USDOT), Bureau of Transportation Statistics (BTS), 1997 Commodity Flow Survey data. Export and import data-USDOT BTS, Transborder Surface Freight Data; and U.S. Department of Commerce, U.S. Census Bureau, Foreign Trade Division, U.S. Exports and Imports of Merchandise CD, December 1997 and 2001.