|Mode||Value Billions of 1997 $||Percent||Tons Millions||Tons Percent||Ton-miles Billions||Ton-miles Percent|
|Truck (for-hire,private, both)||5,336||62.3||8,836||59.7||1,109||28.8|
|Parcel, postal,courier services||856||10.0||34||0.2||18||0.5|
|Air (includes truck and air)||653||7.6||10||0.1||6||0.2|
|Rail (includestruck and air)||436||5.1||1,676||11.3||1,132||29.4|
|Other andunknown modes||293||3.4||576||3.9||204||5.3|
a Data from the Commodity Flow Survey (CFS), plus Bureau of Transportation Statistics estimates to fill in CFS gaps. The estimates cover out-of-scope farm-based truck shipments, truck and rail imports from Canada and Mexico, and air cargo and water imports and exports.
Sources: U.S. Department of Transportation, Bureau of Transportation Statistics and U.S. Department of Commerce, Census Bureau, 1997 Commodity Flow Survey: United States (Washington, DC: December 1999); and Oak Ridge National Laboratory data.