| Mode | 1970 | 1980 | 1990 | 1999 | 2000 |
|---|---|---|---|---|---|
| Air carriers | 2,679 | 3,808 | 6,083 | 8,228 | U |
| General aviation | 131,743 | 211,045 | 196,800 | 219,464 | U |
| Passenger carsa | 89,243,557 | 121,600,843 | 133,700,496 | 132,432,044 | 133,621,420 |
| Motorcycles | 2,824,098 | 5,693,940 | 4,259,462 | 4,152,433 | 4,346,068 |
| Other 2-axle, 4-tire vehicles | 14,210,591 | 27,875,934 | 48,274,555 | 75,356,376 | 79,084,979 |
| Trucks: Single-unit | 3,681,405 | 4,373,784 | 4,486,981 | 5,762,864 | 5,926,030 |
| Combination | 905,082 | 1,416,869 | 1,708,895 | 2,028,562 | 2,096,619 |
| Busesb | 377,562 | 528,789 | 626,987 | 728,777 | 746,125 |
| Passenger rail | |||||
| Amtrak-Cars | N | 2,128 | 1,863 | 1,992 | 1,894 |
| Locomotives | N | 419 | 318 | 329 | 378 |
| Commuter railcarsand locomotives | N | 4,500 | 4,415 | P4,883 | |
| Transitc | 10,548 | 10,654 | 11,332 | P11,603 | U |
| Class I rail: | |||||
| Freight cars | 1,423,921 | 1,168,114 | 658,902 | 579,140 | 560,154 |
| Locomotives | 27,077 | 28,094 | 18,835 | 20,256 | 20,028 |
| Other freight cars | 360,260 | 542,713 | 553,359 | 789,696 | 820,642 |
| Nonself-propelled vesselsd,e | 19,377 | 31,662 | 31,209 | 33,387 | U |
| Self-propelled vesselsd,e | 6,455 | 7,126 | 8,236 | 8,379 | U |
| Oceangoing shipse (1,000 gross tons and over) | 1,579 | 864 | 636 | 463 | 447 |
| Recreational boatsf | 7,400,000 | 8,577,857 | 10,996,253 | 12,738,271 | 12,782,143 |
a In July 1997, the U.S. Department of Transportation, Federal Highway Administration, reassigned some vehicles from "passenger car" to "other 2-axle, 4-tire."
b Includes municipally owned transit, commercial, federal, and school buses.
c Includes light and heavy rail only.
Key: N = data do not exist; P = preliminary; U = unavailable.
Source: Various sources, as cited in U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics 2001, table 1-9, available Spring 2002 at www.bts.gov, or email to answers@bts.gov.