|Air carrier, domestic, scheduled service||33.01||34.13||40.65||53.64||84.60||92.53||107.86||106.78||103.60||109.80||103.21||106.66||110.37||114.10||114.34||114.98||121.27||111.60||101.94||103.75||103.59||106.27||(R)113.46||108.36|
|Class I bus, intercitya||2.46||2.73||3.81||5.46||10.57||11.98||20.22||21.86||21.15||21.32||19.77||20.10||22.85||20.83||23.14||26.16||29.46||30.27||30.11||U||U||U||U||U|
|Transit, all modesb (unlinked)||0.14||0.16||0.22||0.27||0.30||0.53||0.67||0.70||0.72||0.77||0.85||0.88||0.93||0.90||0.91||0.90||0.93||0.92||0.90||0.97||1.02||1.05||1.12||1.09|
|Intercity rail / Amtrakc||4.22||3.92||3.19||12.96||17.72||26.15||39.59||41.19||40.78||40.11||39.10||39.92||43.31||45.26||44.75||46.85||49.61||51.58||55.15||50.68||(R)50.04||(R)51.47||56.45||58.94|
KEY: R = revised; U = data are unavailable.
a Regular route intercity service.
b Prior to 1984, excludes commuter railroad, automated guideway, urban ferryboat, demand responsive, and most rural and smaller systems.
c Amtrak began operations in 1971.
Air carrier, domestic, scheduled service:
1960: Civil Aeronautics Board, Handbook of Airline Statistics, 1969 (Washington, DC: February 1970), part III, table 2 (enplanements); part IV, table 2 (passenger revenue).
1965-70: Ibid. Handbook of Airline Statistics, 1973 (Washington, DC: March 1974), part III, table 2 (enplanements); part IV, table 2 (passenger revenue).
1975-80: Ibid. Air Carrier Financial Statistics (Washington, DC: Annual December issues), p. 1, line 3; and Air Carrier Traffic Statistics (Washington, DC: Annual December issues), p. 2, line 16 (passenger revenue / revenue passenger enplanements).
1985-2007: U.S. Department of Transportation, Bureau of Transportation Statistics, Office of Airline Information, Air Carrier Financial Statistics (Washington, DC: Annual December issues); and Air Carrier Traffic Statistics (Washington, DC: Annual December issues) (passenger revenue / revenue passenger enplanements).
Class I bus, intercity:
1960-93: Interstate Commerce Commission, Transport Statistics in the United States, Motor Carriers (Washington, DC: Annual issues), part 2.
1994-2002: U.S. Department of Transportation, Bureau of Transportation Statistics, Selected Earnings Data, Class I Motor Carriers of Passengers (Washington, DC: Annual issues) (operating revenue / revenue passengers).
Transit and commuter rail:
1960-2007: American Public Transportation Association, Public Transportation Fact Book Appendix A: Historical Tables (Washington, DC: Annual issues), table 43, and similar tables in earlier editions (passenger fares / passenger trips).
Intercity rail / Amtrak:
1960-70: Association of American Railroads, Railroad Facts (Washington, DC: Annual issues).
1975-80: Amtrak, State and Local Affairs Department and Public Affairs Department, personal communication.
1985: Amtrak, Amtrak Annual Report, Statistical Appendix (Washington, DC: Annual issues) (transportation revenues / Amtrak system passenger trips).
1990-2007: Amtrak, Amtrak Annual Report, Annual Statistical Report (Washington, DC: Annual issues) (ticket revenue per passenger mile x average trip length of passengers).