|Mode||Value (1997 $billions)||Tons (millions)||Ton-miles (billions)|
|Truck (private and for-hire)||5,336||8,836||1,109|
|Parcel, postal, and courier||856||34||18|
|Air (including truck and air)||653||10||6|
|Rail (including truck and rail)||436||1,676||1,132|
|Other and unknown||293||576||204|
SOURCE: U.S. Department of Transportation, Bureau of Transportation Statistics and U.S. Department of Commerce, U.S. Census Bureau,1997 Commodity Flow Survey, United States, EC97TCF-US (Washington, DC: 1999); and Oak Ridge National Laboratory data.