|Type of trips||Total trips* (rounded to nearest billion)||Total miles** (rounded to nearest billion)|
|All person trips||411||4,012|
|Person trips by PV||356||3,552|
SOURCE: The 2001 National Household Travel Survey, daily trip file, U.S. Department of Transportation.
* In order to correctly calculate miles per trip, denominators of 403, 350, and 233 billion trips were used for all person trips, personal vehicle person trips and vehicle trips respectively since not all cases had reported mile values associated with them.
** The total mileage represents daily household-based travel and therefore does not reflect a total of all passenger miles of travel in the United States. It does not include a) vehicle mileage from nondaily long-distance trips, b) noncommuting occupational trips (e.g., taxi cab driving), and c) is also subject to a small amount of nonresponse in trip mileage reporting by survey respondents.
See table A-8 for standard errors.