The 2001 NHTS was sponsored by the Bureau of Transportation Statistics and the Federal Highway Administration of the U.S. Department of Transportation. Households were asked about all the trips1 they took on a specific day (daily travel), known as the "travel day," and about trips from home to a distance of at least 50 miles in the 27 days preceding and including the travel day, known as the "travel period." Detailed characteristics were collected for each trip including, among other things, the mode of transportation, the purpose of the trip, and the distance traveled. Additionally, households were asked to provide information about their social and demographic characteristics, including income and vehicle ownership, as well as the age, sex, education level, and so forth of household members. The 2001 NHTS collected information from 26,000 households nationally between March 2001 and May 2002. NHTS passenger data differ from data presented in section 1, "Passenger-Miles of Travel." See box 1-A for a discussion of these differences.
While many aspects of the survey are consistent across its daily and long-distance trip components, differences exist. In addition to the period over which the data were collected, the definition of a trip is also different. Daily travel (as defined in footnote 1) also counted walking and bicycling trips for recreation, including walking the dog, where a person starts and ends at the same address. Thus, daily travel covers trips that do not necessarily originate from home, such as trips from work to the doctor. Long-distance trips, by contrast, are defined as trips originating from home and include the return component from the farthest destination, as well as any overnight stops and stops to change transportation mode.
Other minor differences exist between the daily and long-distance components of the NHTS. For instance, data collected on long-distance trips do not include travel time and the time of day the trip took place, but do include the location of overnight stops and access/egress to an airport, train station, bus station, or boat pier.
1 A trip is defined as traveling from one address to another, whether it is down the street, across town, or cross country.