($ millions)
| 1999 | 2000 | 2001 | 2002 | 2003 | |
|---|---|---|---|---|---|
| Truck | 30,219 | 32,770 | 29,955 | 32,876 | 35,720 |
| Rail | 18,584 | 24,645 | 22,914 | 22,376 | 22,889 |
| Pipeline | 969 | 2,280 | 2,764 | 2,102 | 3,637 |
| Other and unknown | 5 | 8 | 14 | 16 | 48 |
| Total | 49,777 | 59,704 | 55,648 | 57,370 | 62,294 |
SOURCE: U.S. Department of Transportation, Bureau of Transportation Statistics, Transborder Surface Freight Data, 1999-2003.