4-2,,,,
"Number of Aircraft, Railcars, Vehicles, and Vessels: 1990–2006",,,,
Mode,1990,2000,R2005,2006
Air,,,,
Air carrier,"6,083","8,055","8,225",U
General aviation,"198,000","217,533","224,352","221,943"
Highway,,,,
Automobiles,"133,700,496","133,621,420","136,568,083","135,399,945"
"Other 2-axle, 4-tire vehiclesa","48,274,555","79,084,979","95,336,839","99,124,775"
"Buses (municipally owned transit and commercial, federal, and school buses)","626,987","746,125","807,053","821,959"
Motorcycles ,"4,259,462","4,346,068","6,227,146","6,686,147"
Trucks,,,,
Single-unit,"4,486,981","5,926,030","6,395,240","6,649,337"
Combination,"1,708,895","2,096,619","2,086,759","2,169,670"
Rail—Passenger,,,,
Amtrak–Cars,"1,863","1,894","1,186","1,191"
Amtrak–Locomotives,318,378,258,319
Commuter railcars and locomotives ,"5,007","5,498","6,392","6,403"
Transitb,"11,332","12,168","12,755","12,853"
Rail—freight,,,,
Class I–Freight cars,"658,902","560,154","474,839","475,415"
Class I–Locomotives,"18,835","20,028","22,779","23,732"
Other freight cars,"553,359","820,642","837,406","871,092"
Waterborne,,,,
"Nonself-propelled vessels (barges)c,d","31,209","33,152","32,052","32,211"
"Self-propelled vesselsc,d","8,236","8,202","8,976","8,898"
"Oceangoing shipsd (1,000 gross tons and over)    ",636,454,357,286
Recreational boats (numbered boats),"10,996,253","12,782,143","12,942,414","12,746,126"
"a Includes vans, pickup trucks, sport utility vehicles, and other 2-axle, 4-tire motor vehicles that are not passenger cars. b Includes light and heavy rail transit only. c See Glossary for definitions. d U.S.-flag vessels.        ",,,,
"Key: R = revised, U = unavailable.",,,,
Note: Other Freight Cars data for 2005 are revised. Transit and Commuter Rail data for 2006 are preliminary.,,,,
"Sources: Air—Federal Aviation Administration, Highway—Federal Highway Administration, Rail: Amtrak and Association of American Railroads, Transit—American Public Transit Association, Waterborne—U.S. Army, Corps of Engineers and  U.S. Coast Guard as cited in U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics, National Transportation Statistics, table 1-11, available at http://www.bts.gov as of January 2009.",,,,