Table 1
Highways: 2000 Data (unless noted)
Public roads 
"46,677 miles of Interstate highways "
"114,511 miles of other National Highway System (NHS) roads"
"3,789,927 miles of non-NHS roads"
Vehicles and use 
"134 million cars, driven 1.6 trillion miles "
"79 million light trucks, driven 0.9 trillion miles"
"8 million commercial trucks with 6 tires or more and combination trucks, driven 0.2 trillion miles"
"746,000 buses (all types), driven 7.6 billion miles"
"4.3 million motorcycles, driven 10.5 billion miles"
Passenger and freight motor carriers
"4,000 private motorcoach companies operating in the U.S. and Canada (1999), 860 million passengers1  (1999)"
"511,000 interstate freight motor carriers,2 "
1.1 trillion ton-miles carried3 
"1 American Bus Association, Motorcoach Census 2000, available at http://www.buses.org, as of Mar. 27, 2002."
"2 U.S. Department of Transportation, Federal Motor Carrier Safety Administration, analysis and information online, “SafeStat Online,” available at http://ai.volpe.dot.gov/SafeStat/safestatmain.asp, as of September 2001."
"3 Eno Foundation, Inc., Transportation in America, 2000 (Washington, DC: 2001)."
"SOURCE: U.S. Department of Transportation, Federal Highway Administration, Highway Statistics 2000 (Washington, DC: 2001), tables HM-15 and VM-1, also available at http://www.fhwa.dot.gov/ohim/hs00/ index.htm, as of Mar. 26, 2002."