NOTES: To make it easier to compare data of differing magnitudes over time, the Bureau of Transportation Statistics divided the data for all years in each category (see table 14-8 in appendix B) by the initial year value and multiplied the result by 100.
SOURCES: U.S. Department of Transportation (USDOT), Research and Innovative Technology Administration, Bureau of Transportation Statistics (BTS), calculations based on data from the following sources. Passenger-miles traveled and energy use (except transit)—USDOT, BTS, National Transportation Statistics 2004, tables 4-6 and 4-8, available at http://www.bts.gov/, as of March 2005. Transit energy use—American Public Transportation Association, Public Transportation Fact Book 2005 (Washington, DC: 2005), tables 34 and 35. Ton-miles—see table 1-12 in appendix B.