Table 2
Air: 1999 Data (unless noted)

Airports (2000)
" 5,317 public-use airports"
" 13,964 private-use airports"
Airports serving large certificated carriers1
" 29 large hubs (69 airports), 458 million enplaned passengers"
" 31 medium hubs (48 airports), 96 million enplaned passengers"
" 56 small hubs (73 airports), 39 million enplaned passengers"
" 577 nonhubs (604 airports), 17 million enplaned passengers "
Aircraft
" 8,111 certificated air carrier aircraft,2 5.1 billion domestic "
  miles flown3 
" 205,000 active general aviation aircraft4 (1998), 3.9 billion "
  statute-miles flown5 (1997)
Passenger and freight companies3
 81 carriers
 588 million domestic revenue passenger enplanements
 13.9 billion domestic ton-miles of freight
Certificated air carriers (domestic and international)
" Majors: 13 carriers, 650,000 employees, 552 million revenue "
  passenger enplanements
" Nationals: 30 carriers, 66,000 employees, 87 million revenue "
  passenger enplanements
" Regionals: 38 carriers, 9,000 employees, 11 million revenue "
  passenger enplanements
"1 U.S. Department of Transportation, Bureau of Transportation Statistics, Office of Airline Information, Airport Activity Statistics of Certificated Air Carriers, 12 Months Ending December 31, 1999 (Washington, DC: 2001)."
"2 Aerospace Industries Association, Aerospace Facts and Figures (Washington, DC: 1999/2000). "
"3 U.S. Department of Transportation, Bureau of Transportation Statistics, Office of Airline Information, Air Carrier Traffic Statistics (Washington, DC: 1999)."
"4 U.S. Department of Transportation, Federal Aviation Administration, General Aviation and Air Taxi Activity and Avionics Survey, Calendar Year 1998 (Washington, DC: 2000)."
"5 U.S. Department of Transportation, Federal Aviation Administration, General Aviation and Air Taxi Activity and Avionics Survey, Calendar Year 1997, FAA-APO-99-4 (Washington, DC: 1999)."

"SOURCE: U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics 2000 (Washington, DC: 2001)."