Table 8,,,,,,
Vehicle-Miles,,,,,,
(Millions),,,,,,
Mode,,1970,1980,1990,1995,1999
Air carriers ,,"2,068","2,523","3,963","4,629","5,309"
General aviation,,"3,207","5,204","4,830","3,795",U
Passenger carsR ,,"916,700","1,111,596","1,408,286","1,428,497","1,569,270"
MotorcyclesR,,"2,979","10,214","9,557","9,797","10,584"
"Other 2-axle, ",,,,,,
"4-tire vehiclesa,R",,"123,286","290,935","574,571","790,029","901,121"
Trucks:,,,,,,
,Single-unitR,"27,081","39,813","51,901","62,705","70,311"
,CombinationR,"35,134","68,678","94,341","115,451","132,386"
"Busesb,R ",,"4,544","6,059","5,726","6,420","7,663"
Otherc,,N,15,R326,R547,U
Rail:,,,,,,
,Transitd,441,403,561,572,U
,Commuter,N,179,213,238,U
,Class 1 freighte,"29,890","29,277","26,159","30,383","33,851"
,"Intercity/Amtrake,f",690,235,301,292,U

"a In July 1997, the U.S. Department of Transportation, Federal Highway Administration, reassigned some vehicle-miles from Òpassenger carÓ to Òother 2-axle, 4-tire.Ó ",,,,,,
"b Includes municipally owned transit, commercial, federal, and school buses. ",,,,,,
"c Includes demand responsive, ferry boat, and other transit not specified; 1980 data include Òother transitÓ only. ",,,,,,
d Includes light and heavy rail only. ,,,,,,
e Car-miles ,,,,,,
f Fiscal year data. Amtrak began operations in 1971. ,,,,,,
Key: N = data do not exist; R = revised; U = unavailable.,,,,,,

"Sources: U.S. Department of Transportation (USDOT), Bureau of Transportation Statistics (BTS), National Transportation Statistics 2000 (Washington, DC: In press), table 1Ð29; USDOT, BTS, Office of Airline Information, Air Carrier Traffic Statistics (Washington, DC: 2000); USDOT, Federal Highway Administration, Highway Statistics 1999 (Washington, DC: 2000); and Association of American Railroads, Railroad Facts,1999 (Washington, DC: 2000).",,,,,,