|Metric tons (thousands)|
NOTES: Import and export tonnage helps identify the volume of cargo flowing through U.S. ports and the resulting vessel traffic on U.S. coastal waters. It also helps identify needs for intermodal truck and rail traffic. Most U.S. coastal ports handle both foreign and domestic cargoes.
A metric ton is equal to 2,204.6 pounds.
SOURCES: April 1998-December 2005: U.S. Department of Transportation, Maritime Administration, U.S. Foreign Waterborne Transportation Statistics Data, September 2006. January 2006-present: U.S. Department of Commerce, U.S. Census Bureau, Foreign Trade Statistics, available at http://www.census.gov/foreign-trade/statistics/index.html as of August 2008.