NOTE:
These data reflect U.S. import and export trade with Canada and Mexico.
Weights of export shipments by land modes are not collected in the
administrative records that provide U.S. trade data. The Bureau of
Transportation Statistics has estimated the land mode export tonnage using
value-to-weight ratios derived from imported commodities.
SOURCE: U.S. Department of Transportation, Research and
Innovative Technology Administration, Bureau of Transportation Statistics,
Transborder Freight Data, as of April 2006.
