(Thousands of metric tons)
|Total trade with Canada||N||N||N|
|Exports to Canada||N||N||N|
|Imports from Canada||N||N||N|
|Total trade with Mexico||N||N||N|
|Exports to Mexico||N||N||N|
|Imports from Mexico||N||N||N|
KEY: N = Data are nonexistent.
Imports from Canada: The U.S. Customs Service began to require shipping weight for U.S. imports from Canada by all modes of transportation in 1990. However, it did not become possible to disaggregate the land modes (road, rail and pipeline) until 1994.
Imports from Mexico: The U.S. Customs Service began to require shipping weight for U.S. imports from Mexico by land modes of transportation (road, rail and pipeline) in April 1995.
Road, rail and pipeline exports: For 1990, 1995 and 1996, the U.S. Census Bureau did not require shippers to report weight for export shipments to Canada or Mexico for these modes of transportation.
Total trade: U.S. Department of Commerce. U.S. Census Bureau. Statistical Abstract of the United States. (Washington, DC: 1990, 1995 and 1996).
Air and water: U.S. Department of Commerce. U.S. Census Bureau. Foreign Trade Division. FT920 U.S. Merchandise Trade. (Washington, DC: December 1990, 1995 and 1996).
Road, rail and pipeline: U.S. Department of Transportation. Bureau of Transportation Statistics. Transborder Surface Freight Data. (Washington, DC: 1998).