In the United States, numerous agencies are involved in the collection, processing, and dissemination of international trade and transportation data. No one dataset provides all the information needed by the transportation community, and multiple sources were used for this report. The integration of these different data sources provides a more complete picture of U.S. international trade and transportation flows and trends. Challenges arise when using multiple data sources, including variations in accuracy, reliability, time series, and data definitions.
This report uses trade data from several sources: the U.S. Census Bureau's U.S. Merchandise Trade data, the Bureau of Economic Analysis' (BEA) balance of payments trade data, the Bureau of Transportation Statistics' (BTS) Transborder Surface Freight Data and Office of Airline Information (OAI) air cargo data, and the U.S. Customs and Border Protection's (CBP) border-crossing data.
Data on U.S. total international merchandise trade and trade by air and water modes are from the Census Bureau's Foreign Trade Division. U.S. total merchandise trade data in inflation-adjusted terms are from the BEA. Inflation-adjusted data, however, are unavailable for imports and exports and for mode of transportation details. Consequently, this report uses current dollar data for most of the trade discussions. Data on merchandise trade transported by all land modes, including data on origins and destinations of the trade flows, are from the BTS Transborder Surface Freight Data, which are currently obtained from the U.S. Census Bureau.
This report also uses CBP data on vehicle crossings into the United States from Canada and Mexico. These data represent the number of incoming truck and trains crossings, both loaded and unloaded. The data do not count individual unique vehicles. For example, one truck may cross the border many times in one day. Each incoming crossing is counted. These data do not provide information on the goods carried by the trucks and trains or their U.S. destinations.
Traded goods usually move by more than one mode of transportation from origin to final destination. In U.S. trade statistics, the export mode of transportation is the mode used when the U.S. international border is crossed. For imports, the mode of transportation is the last mode used when the freight was transported to the U.S. port of clearance or entry. The available trade data do not distinguish goods moved by intermodal combinations.
For additional information see:
U.S. Department of Transportation, Bureau of Transportation Statistics, U.S. International Trade and Freight Transportation Trends, Appendix B, Washington, DC: 2003.
U.S. Department of Transportation, Bureau of Transportation Statistics, North American Trade and Travel Trends, Washington, DC: 2002.