KEY: NPIAS = National Plan of Integrated Airport Systems.
NOTES: There are 546 commercial service airports. There are 3,364 NPIAS airports, including the commercial serivice airports. Data only available for years shown. Raw data not readily available.
SOURCE: U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics 2002 (Washington DC: 2003), also available at http://www.bts.gov/, as of January 2003. Based on data obtained from the U.S. Department of Transportation, Federal Aviation Administration, Office of Airport Planning and Programming, National Planning Division, personal communication, 2003.