ORNL/TM-2004/297

Summary of Travel Trends

2001 National Household Travel Survey

December 2004
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ORNL/TM-2004/297

Summary of Travel Trends

2001 National Household Travel Survey

December 2004

Patricia S. Hu

Center for Transportation Analysis

 Oak Ridge National Laboratory

and

Timothy R. Reuscher

MacroSys Research and Technology

Prepared for

U.S. DEPARTMENT OF TRANSPORTATION

Federal Highway Administration

Washington, D.C. 20590

Prepared by

OAK RIDGE NATIONAL LABORATORY

Oak Ridge, Tennessee 37831-6285

managed by

UT-BATTELLE, LLC

for the

U.S. DEPARTMENT OF ENERGY

under contract DE-AC05-00OR22725

2001 NHTS Summary of Travel Trends (DRAFT) Table of Contents

v

TABLE OF CONTENTS

LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

INTRODUCTION .............................................................1

PROFILE OF THE 2001 NHTS ..................................................2

IMPROVEMENTS IN THE NPTS/NHTS SERIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

REPORT ORGANIZATION .....................................................5

TRAVEL AND DEMOGRAPHIC SUMMARY .....................................9

HOUSEHOLD TRAVEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

PERSON TRAVEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

PRIVATE VEHICLE TRAVEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

VEHICLE AVAILABILITY AND UTILIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

COMMUTE TRAVEL PATTERNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

TEMPORAL DISTRIBUTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

TRAVEL BEHAVIOR OF SUB-POPULATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

TRAVEL CONCEPTS AND GLOSSARY OF TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-1

APPENDIX 1. SELECTED TABLES INCLUDING TRAVEL OF INDIVIDUALS 

0 to 4 YEAR-OLDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1-1

APPENDIX 2. KEY CHANGES IN THE 2001 NHTS SURVEY METHODOLOGY

AND CONTENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A2-1

APPENDIX 3. ADJUSTMENT OF 1990 TRAVEL DATA . . . . . . . . . . . . . . . . . . . . . . . . A3-1

APPENDIX 4. SELECTED STANDARD ERROR TABLES . . . . . . . . . . . . . . . . . . . . . . . A4-1
Table of Contents 2001 NHTS Summary of Travel Trends (DRAFT)

vi

APPENDIX 5. DIFFERENCES IN METROPOLITAN AREA DEFINITIONS

BETWEEN 1983 AND 1990 NPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A5-1
2001 NHTS Summary of Travel Trends (DRAFT) List of Tables

vii

LIST OF TABLES

Travel and Demographic Summary

Table 1. Summary Statistics on Demographic Characteristics and Total Travel,

1969, 1977, 1983, 1990, and 1995 NPTS, and 2001 NHTS ....................9

Table 2 Summary of Demographic Trends, 1969, 1977, 1983, 1990, 

and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Table 3. Summary of Travel Trends, 1969, 1977, 1983, 1990, 

and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Table 4. Comparison of Survey Variables with Other Sources . . . . . . . . . . . . . . . . . . . . . . . . 14

Household Travel

Table 5. Average Annual PMT, Person Trips and Trip Length by Trip Purpose,

1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table 6. Average Annual VMT, Vehicle Trips and Trip Length by Selected Trip Purposes,

1969, 1977, 1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . 16

Table 7. Average Annual Person Trips per Household by Mode of Transportation 

and MSA Size, 1977, 1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . 17

Table 8. Person Trips per Household by Household Income, 1983, 1990, 

and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Person Travel

Table 9. Total Person Trips by Mode of Transportation and Trip Purpose,

 Adjusted 1990 and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Table 10. Person Trips per Person by Trip Purpose and Gender,

 Adjusted 1990 and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Table 11. Daily Trip Rates per Person by Trip Purpose, 1977, 1983, 1990, 

and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Table 12. Distribution of Daily Person Miles of Travel per Person by Mode of 

Transportation and Trip Purpose, Adjusted 1990 and 1995 NPTS, and 2001 NHTS 23

Table 13. Average Daily Person Trips per Person by Age and Gender,

1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
List of Tables 2001 NHTS Summary of Travel Trends (DRAFT)

viii

Table 14. Average Daily Person Miles of Travel per Person by Age and Gender,

1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Private Vehicle Travel

Table 15. Average Time Spent Driving a Private Vehicle in a Typical Day by MSA Size,

Adjusted 1990 and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Table 16. Average Vehicle Occupancy for Selected Trip Purposes, 

1977, 1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . 31

Vehicle Availability and Utilization

Table 17. Availability of Household Vehicles, 1969, 1977, 1983, 1990, 

and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Table 18. Distribution of Households by Household Vehicle Availability and 

Population Density, 1990 and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . 34

Table 19. Percent of Households Without a Vehicle Within MSA Size Group,

1977, 1983, 1990 and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . 36

Table 20. Vehicle Distribution and Average Vehicle Age by Vehicle Type,

1977, 1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . 37

Table 21. Distribution of Vehicles by Vehicle Age and Vehicle Type, 

1969, 1977, 1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . 38

Table 22. Average Annual Miles per Vehicle by Vehicle Age,

1969, 1977, 1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . 40

Table 23. Average Annual Miles per Licensed Driver by Driver Age and Gender,

1969, 1977, 1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . 41

Commute Travel Patterns

Table 24. Commute VMT and Total VMT By Year, 1969, 1977, 

 1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Table 25. Distribution of Workers by Usual Mode, 1969, 1977, 1983, 1990, 

and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Table 26. General Commute Patterns by Mode of Transportation, 1983, 1990, 

and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2001 NHTS Summary of Travel Trends (DRAFT) List of Tables

ix

Table 27. Average Commute Speed by MSA Size, 1983, 1990, and 1995 NPTS, and 2001

NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Temporal Distribution

Table 28. Distribution of Person Trips by Start Time of Trip, 1983, 1990, 

and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Table 29. Daily Travel Statistics by Weekday vs Weekend, Adjusted 1990 

and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Travel Behavior of Sub-Populations

Table 30. Daily Travel Statistics of People 65 and Older, 1983, 1990, and 1995 NPTS, and 

2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Table 31. Daily Person Trips of Adult Women by Household Composition,

1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Table 32. Daily Person Trips per Person for Low Income Households by Trip Purpose,

1983, 1990, and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Table 33. Daily Person Trips per Person by Vehicle Ownership Status and MSA Size,

Adjusted 1990 and 1995 NPTS, and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
List of Tables 2001 NHTS Summary of Travel Trends (DRAFT)

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2001 NHTS Summary of Travel Trends (DRAFT) List of Figures

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LIST OF FIGURES

Travel and Demographic Summary

Figure 1. Changes in Summary Demographics, 1969, 1977, 1983, 1990, 1995 NPTS, 

and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Person Travel

Figure 2. Distribution of Person Trips per Person by Gender and Trip Purpose,

1995 NPTS and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 3. Average Daily Person Trips by Age and Gender From 1995 to 2001 . . . . . . . . . . . . 25

Figure 4. Average Daily Person Miles of Travel per Person by Gender, 1995 NPTS

and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Figure 5. Average Time Spent in Vehicle (Minutes) by Age, 2001 NHTS . . . . . . . . . . . . . . . 28

Figure 6. Average Time Spent in Vehicle and Miles Traveled, 1995 NPTS and 2001 NHTS . 29

Vehicle Availability and Utilization

Figure 7. Household Distribution by Household Income and Vehicle to Driver Ratio,

2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 8. Vehicle Ownership and Demographic Statistics by Population Density, 2001

NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 9. Distribution of Vehicles by Vehicle Age 1977, 1983, 1990, 1995 NPTS, and

2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
List of Figures 2001 NHTS Summary of Travel Trends (DRAFT)

xii

Commute Travel Patterns

Figure 10. Distribution of Workers by Usual Mode, 1995 NPTS and 2001 NHTS . . . . . . . . . . 43

Figure 11. Average Commute Time in Privately-Owned Vehicles and MSA Size, 1995 NPTS

and 2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Figure 12. Average Commute Speed for Selected Time of Day by MSA Size, 

2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Temporal Distribution

Figure 13. Distribution of Person Trips by Trip Purpose and Start Time of Trip,

2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Travel Behavior of Sub-Populations

Figure 14. Mode Distribution of Person Trips Taken by Zero-Vehicle Households,

2001 NHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
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Summary of Travel Trends

2001 National Household Travel Survey
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2001 NHTS Summary of Travel Trends (DRAFT) Introduction

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Summary of Travel Trends

2001 National Household Travel Survey

INTRODUCTION

Policymakers rely on transportation statistics, including data on personal travel behavior, to

formulate strategic transportation policies and to improve the safety and efficiency of the U.S.

transportation system. Data on personal travel trends are needed to examine the reliability,

efficiency, capacity, safety, and flexibility of the nation’s transportation system to meet current

demands and accommodate future demands; to assess the feasibility and efficiency of alternative

congestion alleviating technologies (e.g., high-speed rail, magnetically levitated trains, intelligent

vehicle and highway systems); to evaluate the merits of alternative transportation investment

programs; and to assess the energy-use and air-quality impacts of various policies.

To address these data needs, the U. S. Department of Transportation (USDOT) initiated an

effort in 1969 to collect detailed data on personal travel. The 1969 survey was the first Nationwide

Personal Transportation Survey (NPTS). The survey was conducted again in 1977, 1983, 1990, and

1995. In 2001, the survey was expanded by integrating the Federal Highway Administrationmanaged NPTS and the Bureau of Transportation Statistics-sponsored American Travel Survey

(ATS). The survey was re-named to the National Household Travel Survey (NHTS).

The 2001 NHTS is the nation’s inventory of daily and long-distance travel. The survey

includes demographic characteristics of households, people, vehicles, and detailed information on

daily and longer-distance travel for all purposes by all modes. NHTS survey data are collected from

a sample of U.S. households and expanded to provide national estimates of trips and miles by travel

mode, trip purpose, and a host of household attributes. When combined with historical data from

1969 through 1995, the 2001 NHTS survey data provide a rich source of detailed information on
Introduction 2001 NHTS Summary of Travel Trends (DRAFT)

2

personal travel patterns over time.

PROFILE OF THE 2001 NHTS

Coverage. The NHTS collected travel data from a national sample of the civilian, noninstitutionalized population of the United States. Sampling was done by creating a

random-digit dialing (RDD) list of telephone numbers. An eligible household

excludes telephones in motels, hotels, group quarters, such as nursing homes,

prisons, barracks, convents or monasteries and any living quarters with 10 or more

unrelated roommates.

Telephones in dorm rooms, fraternity and sorority houses were eligible for sampling,

provided that the residence had less than 11 household members sharing the same

phone line. Therefore, students who normally reside at school but were living at

home for the summer were not considered household members at their parent's home.

Household members included people who think of the sampled household as their

primary place of residence. It included persons who usually stay in the household

but were temporarily away on business, vacation, or in a hospital. It did not include

people just visiting, such as a college student who normally lives away at school.

When The 2001 NHTS for the national and New York and Wisconsin add-ons was

conducted over a period from March 2001 through May 2002. Data collection for

the remaining add-on areas extended to July 2002.

Sample Size. The sample size for the 2001 NHTS was 69,817 households comprised of:

S a national sample of 26,038 completed households, and
2001 NHTS Summary of Travel Trends (DRAFT) Introduction

3

S 43,779 additional households collected for the use of and funded by nine addon areas:

Baltimore, MPO;

Des Moines, MPO;

Hawaii;

Kentucky (4 counties);

Lancaster PA, MPO;

New York State;

Oahu (Honolulu MPO);

Texas state; and

Wisconsin state.

Contents. The NHTS serves as the nation’s inventory of daily personal travel. It includes, but

is not limited to:

S household data on the relationship of household members, education level,

income, housing characteristics, and other demographic information;

S information on each household vehicle, including year, make, model, and

estimates of annual miles traveled and fuel costs;

S data about drivers, including information on travel as part of work;

S data about one-way trips taken during a designated 24-hour period (the

household's designated travel day), including the time the trip began and ended,

length of the trip, composition of the travel party, mode of transportation, purpose

of the trip, and the specific vehicle used (if a household vehicle);

S data describing round-trips taken during a four-week period (the household’s

designated travel period) where the farthest point of the trip was at least 50 miles

from home, including the farthest destination, access and egress stops and

overnight stays on the way to and from the farthest destination, mode, purpose,

and travel party information;
Introduction 2001 NHTS Summary of Travel Trends (DRAFT)

4

S if no long-distance trips were made during the four-week travel period, data on the

most recent long-distance trip by any mode and the most recent long-distance

train trip;

S information to describe characteristics of the geographic area in which the sample

household and workplace of sample persons are located;

S data on telecommuting;

S public perceptions of the transportation system;

S data on Internet usage; and

S the typical number of transit, walk and bike trips made over a period longer than

the 24-hour travel day. 

For more information on the 2001 survey methodology and procedures, please consult: “User’s

Guide for the Public Use Data Files 2001 National Household Travel Survey” available at:

http://nhts.ornl.gov/2001/usersguide/index.shtml

IMPROVEMENTS IN THE NPTS/NHTS SERIES

The US DOT continues to research and embrace improved methodologies to collect more

accurate and more complete travel data, and to increase response rates. Among the changes in the

2001 NHTS, two are especially significant. First, the 2001 survey was the first survey in the

NPTS/NHTS series that collects travel by household members younger than 5 years old. All

previous surveys had collected travel only from household members age 5 and older. To facilitate

compatible trend analysis, information about travel by individuals younger than 5 years old is

excluded in the main body of the report. However, their travel was included in a few key tables that

are presented in Appendix 1.

The second improvement in the 2001 NHTS survey was the improved, multiple prompting

for walk and bike trips. This has significantly increased the number of walk and bike trips recorded.
2001 NHTS Summary of Travel Trends (DRAFT) Introduction

5

A complete comparison between the 1995 and 2001 survey methods is summarized in Appendix 2.

While improvements to the survey process are encouraged, changes in the 1995 survey

method brought about significant data compatibility issues. To address these issues, the 1990 survey

data were adjusted to allow comparison to the 1995 survey. In this report, both the original 1990

data and the adjusted 1990 data are reported to facilitate trends analysis. The reader is advised to

compare the 1969-1983 survey results to the unadjusted 1990 data, and the 1995 and 2001 survey

results to the adjusted 1990 data. The method used to adjust the 1990 travel data is described in

Appendix 3.

REPORT ORGANIZATION

This report highlights important travel trends in tabular and graphic format. Statistics are

categorized by topic. The report begins with a summary of travel and demographic changes. Next,

travel changes are examined from an individual household perspective, then from an individual

person perspective. This report concludes with trip-making statistics of sub-populations such as

women, households without vehicles, low-income households, and the elderly. No attempt is made

in this report to present all of the data or to analyze and discuss the data in any depth. Standard error

estimates for key statistics are presented in Appendix 4.
Introduction 2001 NHTS Summary of Travel Trends (DRAFT)

6

Notes to Users of 2001 NHTS Data

Data Version

Tables in this publication, the 2001 National Household Travel Survey (NHTS) Summary of

Travel Trends, were prepared using the January 2004 release of the NHTS data. This version

of the data includes data from all of the nine add-on areas.

Travel of 0-4 year-olds

In 2001, the travel of 0 to 4 year-olds was measured for the first time. In order to make the

2001 data comparable to that of the previous surveys, the 2001 data reported in all tables

exclude travel of this group of individuals unless explicitly stated otherwise (for example,

Tables 1 and 3). Note that inclusion of travel taken by individuals 0 to 4 year-olds does not

affect the statistics on vehicle trips, or vehicle miles of travel (VMT) because such measures

are derived based on travel taken by the driver of the trip.

To- and From-Work Trips

The number of trips taken to, or from, work dropped substantially from 1995 to 2001. Given

the historical trends between 1990 and 2001, this decrease in the number of work trips could

be attributable to the overestimated work travel in the 1995 survey data.

Data Source Work Trips

(000,000s)

Workers

(000s)

Work Trips

per Worker

Daily Work Trips

per Worker

1990 NPTS 50,314 118,343 425 1.16

1995 NPTS 66,901 131,697 508 1.39

2001 NHTS 60,690 145,272 418 1.14

Walk Trips

Respondents to the 2001 NHTS were specifically prompted to report walk trips. Since this was

not done in the previous surveys, the increases in the number of walk trips can be explained,

at least in part, by this change in methodology.
2001 NHTS Summary of Travel Trends (DRAFT) Introduction

7

Notes to Users (Continued)

Nonresponse Weighting

In the 2001 NHTS, special care was given to nonresponse adjustments in the weighting of the

survey data. This was done to make the weighted survey results more representative of the U.S.

population. For example, these adjustments increase the weighted survey results of low-income

households, thereby help compensate for the low response rate of these households. The

improved weighting for nonresponse may account for part of the reduction, from 1995 to 2001,

in the average number of trips taken by a low-income household.
Introduction 2001 NHTS Summary of Travel Trends (DRAFT)

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2001 NHTS Summary of Travel Trends (DRAFT) Travel and Demographic Summary

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Table 1

Summary Statistics on Demographic Characteristics and Total Travel

1969, 1977, 1983, 1990, and 1995 NPTS, and 2001 NHTS

1969 1977 1983 1990 1990

Adj. 1995 2001 

2001

(includes

0-4)

Percent Change 

69-90

Percent Change

90 (adj.)-01

Comp.

Annual

Total

Change

Comp.

Annual

Total

Change

 Households (000)

 All 62,504 75,412 85,371 93,347 - 98,990 107,365 - 1.9 49 1.3 15

 1 person 10,980 16,214 19,354 22,999 - 24,732 27,718 - 3.6 109 1.7 21

 2 persons 18,448 22,925 27,169 30,114 - 31,834 35,032 - 2.4 63 1.4 16

 3 persons 10,746 13,046 14,756 16,128 - 16,827 17,749 - 2.0 50 0.9 10

 4+ persons 22,330 23,227 24,092 24,106 - 25,597 26,867 - 0.4 8 1.0 11

 Persons (000)

 All 197,213 213,141 229,453 239,416 - 259,994 277,203 - 0.9 21 1.3 16

 Under 16 60,100 54,958 53,682 54,303 - 61,411 64,612 - -0.5 -10 1.6 19

 16-19 14,598 16,552 15,268 13,851 - 14,074 14,296 - -0.2 -5 0.3 3

 20-34 40,060 52,252 60,788 59,517 - 59,494 57,680 - 1.9 49 -0.3 -3

 35-64 62,982 66,988 75,353 82,480 - 93,766 103,296 - 1.3 31 2.1 25

 65+ 19,473 22,391 24,362 26,955 - 31,249 32,884 - 1.6 38 1.8 22

 All 16+ 137,113 158,183 175,771 182,803 198,583 208,155 1.4 33 1.2 14

 All Male 94,465 102,521 111,514 114,441 - 126,553 135,276 - 0.8 21 1.5 18

 All Male -

16+

66,652 74,542 83,645 86,432 - 95,627 100,308 - 1.1 30 1.4 16

 All Female 102,748 110,620 117,939 124,975 - 133,441 141,910 - 0.8 22 1.2 14

 All Female -

16+

73,526 83,721 92,080 96,371 - 102,956 107,847 - 1.1 31 1.0 12

 All - 5+ NA 198,434 212,932 222,101 - 241,675 257,576 - 0.6 12 1.2 14

 All Male 5+ NA 95,050 102,633 106,209 - 117,636 125,321 - 0.6 12 1.4 16

 All Fem. 5+ NA 103,384 110,299 115,892 - 124,039 132,239 - 0.6 13 1.0 12

 Licensed Drivers (000)

 All 102,986 127,552 147,015 163,025 - 176,330 190,425 - 2.2 58 1.4 17

 Male 57,981 66,199 75,639 80,289 - 88,480 94,651 - 1.6 38 1.5 18

 Female 45,005 61,353 71,376 82,707 - 87,851 95,773 - 2.9 84 1.3 16

 Workers (000)

 All 75,758 93,019 103,244 118,343 - 131,697 145,272 - 2.1 56 1.9 23

 Male 48,487 55,625 58,849 63,996 - 71,105 78,264 - 1.3 32 1.8 22

 Female 27,271 37,394 44,395 54,334 - 60,593 67,007 - 3.3 99 1.9 23

 Household Vehicles (000)

72,500 120,098 143,714 165,221 - 176,067 202,586 - 4.0 128 1.9 23

 Household Vehicle Trips (000,000)

87,284 108,826 126,874 158,927 193,916 229,745 233,040 - 2.9 82 1.7 20

 Household VMT (000,000)

775,940 907,603 1,002,139 1,409,600 1,695,290 2,068,368 2,274,797 - 2.9 82 2.7 34

 Person Trips (000,000)

145,146 211,778 224,385 249,562 304,471 378,930 384,484 407,262 2.6 72 2.0 24

 Person Miles of Travel (000,000)

1,404,137 1,879,215 1,946,662 2,315,300 2,829,936 3,411,122 3,783,975 3,972,749 2.4 65 2.5 32

Note:

• All tables reporting totals could include some unreported characteristics.

• Travel statistics for surveys prior to 2001 do not include those by 0-4 year olds. Note that the inclusion of 0-4 year olds in the "2001 (includes 0-4)" column does not affect vehicle

trips or VMT, since such measures are reported by the driver of the trip. Also note that respondents whose age is unknown are included in the "All 5+," "All Male 5+," and "All Female

5+," categories.

• In expanding (weighting) the sample to the total population, slightly different approaches were used in 1990 and 1995. Thus, the growth in the under 16 age group is probably overstated.

Other age groups track closer to Census data.

• Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus, there are limits on the conclusions that can be drawn in comparing

travel with surveys conducted prior to 1990. The adjustments to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).
Travel and Demographic Summary 2001 NHTS Summary of Travel Trends (DRAFT)

1 The 1969 NPTS survey did not include trucks as household vehicles. For comparability

across surveys, the number of household vehicles in 1969 was estimated based on statistics

reported in Highway Statistics. It was assumed that fifty percent of all 2-axle 4-tire vehicles

in 1969 were used for personal purposes, resulting in a total estimate 95,876,000 household

vehicles [=89,173,502 + 50% × 13,405,772]. 

10

1

1.2

1.4

1.6

1.8

2

2.2

1969 1977 1983 1990 1995 2001

(Indexed to 1969 (1969=1))

Vehicles

Drivers

Workers

Households

Population

Figure 1

Changes in Summary Demographics

19691

, 1977, 1983, 1990, 1995 NPTS, and 2001 NHTS 

During the past three decades, the number of vehicles increased at a steeper rate than most

other demographic indicators. For example, it increased at an annual rate that was almost one

and one-half times that of the total number of licensed drivers.
2001 NHTS Summary of Travel Trends (DRAFT) Travel and Demographic Summary

11

Table 2

Summary of Demographic Trends

1969, 1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

1969 1977 1983 1990 1995 2001

Persons per household 3.16 2.83 2.69 2.56 2.63 2.58

Vehicles per household 1.16 1.59 1.68 1.77 1.78 1.89

Licensed drivers per household 1.65 1.69 1.72 1.75 1.78 1.77

Vehicles per licensed driver 0.70 0.94 0.98 1.01 1.00 1.06

Workers per household 1.21 1.23 1.21 1.27 1.33 1.35

Vehicles per worker 0.96 1.29 1.39 1.40 1.34 1.39

Note:

• The 1969 survey does not include pickups and other light trucks as household vehicles.

The typical American household continues to own more vehicles. The percentage of

households who own 3 or more vehicles increased from 19% in 1995 to 23% in 2001 (Table

17). The number of workers per household increased slightly, probably reflecting the trend in

which retirees return to the labor market.
Travel and Demographic Summary 2001 NHTS Summary of Travel Trends (DRAFT)

12

Table 3

Summary of Travel Statistics

1969, 1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

1969 1977 1983 1990

1990

Adj. 1995 2001

2001

(includes trips by

children younger

than 4 year olds)

Per Person

Daily Person Trips 2.02 2.92 2.89 3.08 3.76 4.30 3.74 4.03

Daily PMT 19.51 25.95 25.05 28.56 34.91 38.67 36.89 39.26

Per Driver

Daily Vehicle Trips 2.32 2.34 2.36 2.67 3.26 3.57 3.35 -

Daily VMT 20.64 19.49 18.68 23.69 28.49 32.14 32.73 -

Per Household

Daily Person Trips 6.36 7.69 7.20 7.32 8.94 10.49 9.66 10.39

Daily PMT 61.55 68.27 62.47 67.95 83.06 94.41 95.24 101.38

Daily Vehicle Trips 3.83 3.95 4.07 4.66 5.69 6.36 5.95 -

Daily VMT 34.01 32.97 32.16 41.37 49.76 57.25 58.05 -

Per Trip

Average person trip

length (miles) 9.67 8.87 8.68 9.45 9.47 9.13 10.04 9.94

Average vehicle trip

length (miles) 8.89 8.34 7.90 8.98 8.85 9.06 9.87 -

Note: 

• Average vehicle trip length for 1990, 1995, and 2001 is calculated using only those records with trip mileage information present.

• Note that inclusion of the 0-4 year olds in travel measures does not change vehicle trips or VMT, since such measures are taken

from the driver of the trip.

• The 1969 survey does not include pickups and other light trucks as household vehicles.

• Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus, there are

limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments to 1990 data affect

only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

Despite the improvement in the 2001 survey where particular attention was given to accurately

record walking trips, Americans took fewer trips in 2001 than in 1995. However, this by no

means suggests that Americans became less mobile. Although fewer trips were taken, the trips

were longer in 2001 than in previous years.
2001 NHTS Summary of Travel Trends (DRAFT) Travel and Demographic Summary

13

Table 4 compares data from the NPTS and NHTS, and those from other data sources. Given

its project-specific goals, each data source has its own scope in terms of data collection

method, target population, and data validation and estimation procedures. Therefore,

comparison of NPTS/NHTS data to data from other sources is at best informative but not

conclusive.

Data on the total number of households for year 2001 were estimated by the Bureau of Census

of the U.S. Department of Commerce as reported in the Current Population Survey Report

(March 2001 edition, from Census Bureau Web page, http://www.census.gov). Data on 2001

population were obtained from the Census Bureau Web page, http://www.census.gov. The

NPTS estimated household population; the Bureau of Census measured resident and civilian

population. The Bureau of Census’ estimates are for July 1 of each year.

Data on the number of licensed drivers are reported by the Federal Highway Administration

(FHWA) of the U.S. Department of Transportation (US DOT) in its annual Highway Statistics

(Table DL-22 of the 2001 report). Note that Highway Statistics shows the cumulative number

of driver’s licenses issued, while the NPTS estimates the number of people who hold a driver’s

license. (The Highway Statistics series can be found at:

www.fhwa.dot.gov/ohim/ohimstat.htm.)

The NPTS’s and NHTS’s estimate on vehicles includes all household-based vehicles but

excludes most fleet vehicles, whereas Highway Statistics reports all vehicles (personal and

commercial) categorized by vehicle type (e.g., automobiles, 2-axle, 4-tire trucks, etc.). To

estimate comparable “household-based” vehicles from Highway Statistics, all of the

automobiles, motorcycles, and a percentage of the 2-axle 4-tire trucks are assumed to be

household-based vehicles. The percent 2-axle 4-tire trucks used for personal purposes is

estimated from the Truck Inventory and Use Surveys (TIUS) and varies by year:

1977: 63.21% trucks, from 1977 TIUS

1983: 64.20% trucks, from 1982 TIUS

1990: 72.38% trucks, from 1990 TIUS

1995: 73.90% trucks, from 1992 TIUS 

2001: 74.85% trucks, from 1997 TIUS
Travel and Demographic Summary 2001 NHTS Summary of Travel Trends (DRAFT)

14

Table 4

Comparison of Survey Variables with Other Sources

(thousands)

Households Population

Licensed

Drivers Vehicles

1969

Other Sources 61,806 199,145 108,306 89,174

NPTS 62,504 197,213 102,986 72,500

1977

Other Sources 74,142 218,106 138,121 132,155

NPTS 75,412 213,141 127,552 120,098

1983

Other Sources 83,918 232,086 154,389 152,070

NPTS 85,371 229,453 147,015 143,714

 1990

Other Sources 91,947 247,826 167,015 172,902

NPTS 93,347 239,416 163,025 165,221

1995

Other Sources 97,386 261,538 176,628 180,735

NPTS 98,990 259,994 176,330 176,067

2001

Other Sources 108,209 285,318 191,276 205,551

NHTS 107,365 277,203 190,425 202,586

Note:

• See the previous page for details on sources for other years.

• The 1969 NPTS survey includes only automobiles, station wagons, and

van buses/minibuses as household vehicles.
2001 NHTS Summary of Travel Trends (DRAFT) Household Travel

15

Table 5

Average Annual PMT, Person Trips and Trip Length by Trip Purpose

1983, 1990, 1995 NPTS, and 2001 NHTS

 Trip Purpose 1983 1990 1990 Adjusted 1995 2001 

Average Annual PMT per Household

All Purposes 22,802 24,803 30,316 34,459 35,244

To/From Work 4,586 5,637 5,637 7,740 6,706

Work Related Business 1,354 1,043 1,043 1,987 2,987

Shopping 2,567 2,674 3,343 4,659 4,887

All Other Fam/Per Business 3,311 5,083 7,167 7,381 6,671

School/Church 1,522 1,599 1,599 1,973 2,060

Social and Recreational 8,964 8,567 11,308 10,571 10,586

Other 500 195 214 131 1,216

Average Annual Person Trips per Household

All Purposes 2,628 2,673 3,262 3,828 3,581

To/From Work 537 539 539 676 565

Work Related Business 62 38 38 100 109

Shopping 474 504 630 775 707

All Other Fam/Per Business 456 606 854 981 863

School/Church 310 304 304 337 351

Social and Recreational 728 662 874 953 952

Other 61 20 22 6 30

Average Person Trip Length (miles)

All Purposes 8.68 9.45 9.47 9.13 10.03

To/From Work 8.54 10.65 10.65 11.63 12.11

Work Related Business 21.77 28.20 28.20 20.28 28.26

Shopping 5.41 5.38 5.38 6.08 7.02

All Other Fam/Per Business 7.27 8.55 8.55 7.63 7.84

School/Church 4.90 5.39 5.39 5.98 6.00

Social and Recreational 12.31 13.19 13.19 11.27 11.36

Other 8.22 10.30 10.30 22.83 43.08

Note: 

• 1995 VMT and vehicle trips with “To or From Work” as a trip purpose are believed to be overstated.

• Average person trip length for 1990, 1995, and 2001 is calculated using only those records with trip mileage information present.

• All tables reporting totals could include some unreported characteristics.

• Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus, there are limits on the

conclusions that can be drawn in comparing travel with earlier survey years. The adjustments to 1990 data affect only person trips, vehicle

trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

• See Appendix for 2001 figures including 0 to 4 year-olds.

Compared to 1995, a typical household traveled slightly more miles in 2001. This increase

took the form of fewer, but generally longer trips. The average distance for commuting to

work continued to increase. 
Household Travel 2001 NHTS Summary of Travel Trends (DRAFT)

16

Table 6

Average Annual VMT, Vehicle Trips and Trip Length by Selected Trip Purposes

1969, 1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

Trip Purpose 1969 1977 1983 1990 1990

Adjusted 1995 2001

 Average Annual VMT per Household

All Purposes 12,423 12,036 11,739 15,100 18,161 20,895 21,187

To or From Work 4,183 3,815 3,538 4,853 4,853 6,492 5,724

Shopping 929 1,336 1,567 1,743 2,178 2,807 3,062

Other Fam & Personal Business 1,270 1,444 1,816 3,014 4,250 4,307 3,956

Social and Recreational 4,094 3,286 3,534 4,060 5,359 4,764 5,186

 Average Annual Vehicle Trips per Household

All Purposes 1,396 1,442 1,486 1,702 2,077 2,321 2,171

To or From Work 445 423 414 448 448 553 479

Shopping 213 268 297 345 431 501 459

Other Fam. & Personal Business 195 215 272 411 579 626 537

Social and Recreational 312 320 335 349 460 427 441

 Average Vehicle Trip Length (miles)

All Purposes 8.90 8.35 7.90 8.98 8.85 9.06 9.87

To or From Work 9.40 9.02 8.55 10.97 10.97 11.80 12.08

Shopping 4.36 4.99 5.28 5.10 5.10 5.64 6.74

Other Fam. & Personal Business 6.51 6.72 6.68 7.43 7.43 6.93 7.45

Social and Recreational 13.12 10.27 10.55 11.80 11.80 11.24 11.91

Note: 

C 1995 VMT and vehicle trips with “To or From Work” as a trip purpose are believed to be overstated.

C Average vehicle trip length for 1990, 1995, and 2001 is calculated using only those records with trip mileage information present.

C All purposes includes other purposes not shown above, such as trips to school, church, doctor, dentist, and work-related business

trips.

C All tables reporting totals could include some unreported characteristics.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus, there are

limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments to 1990 data affect

only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

Similar to what was observed in the 1995 survey, commuting had the largest share of vehicle

travel. In the past, social and recreational trips had the longest average driving distance among

all trips. However, this pattern has changed since 1995, with commuting trips becoming the

longest. 
2001 NHTS Summary of Travel Trends (DRAFT) Household Travel

17

Table 7

Average Annual Person Trips per Household

by Mode of Transportation and MSA Size

1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

Mode of Transportation

SMSA or MSA Size 1977 1983 1990 1990 Adjusted 1995 2001

Private

ALL 2,351 2,152 2,329 2,861 3,307 3,090

Not in (S)MSA 2,436 2,322 2,306 2,837 3,492 3,076

Less than 250,000 2,517 2,375 2,508 3,090 3,503 3,304

250,000 - 499,999 2,574 2,443 2,461 3,014 3,472 3,251

500,000 - 999,999 2,628 2,140 2,413 2,957 3,509 3,348

1,000,000 - 2,999,999 2,366 2,031 2,430 2,986 3,354 3,174

3,000,000 and above 1,785 1,691 2,160 2,649 3,075 2,911

PublicTransit

ALL 73 60 52 58 67 58

Not in (S)MSA 22 11 13 14 9 6

Less than 250,000 47 17 27 30 23 12

250,000 - 499,999 44 23 19 22 18 18

500,000 - 999,999 58 48 28 33 33 11

1,000,000 - 2,999,999 86 67 46 52 37 36

3,000,000 and above 189 181 112 124 137 128

Walk

ALL 261 226 193 234 205 309

Not in (S)MSA 199 211 146 175 134 221

Less than 250,000 241 280 172 212 138 248

250,000 - 499,999 206 199 165 203 152 251

500,000 - 999,999 256 184 132 161 138 224

1,000,000 - 2,999,999 295 179 170 207 162 275

3,000,000 and above 396 330 278 337 301 423

ALL MODES

ALL 2,808 2,628 2,673 3,262 3,828 3,581

Not in (S)MSA 2,800 2,766 2,580 3,151 3,878 3,435

Less than 250,000 2,944 2,889 2,816 3,450 3,926 3,678

250,000 - 499,999 2,945 2,891 2,741 3,340 3,894 3,645

500,000 - 999,999 3,049 2,542 2,667 3,252 3,916 3,692

1,000,000 - 2,999,999 2,861 2,463 2,737 3,344 3,795 3,602

3,000,000 and above 2,459 2,326 2,641 3,213 3,765 3,593

Note:

C Increases in Walk trips in 2001 are due, at least in part, to respondents being explicitly asked to include walk trips, which was not the case in prior surveys.

C The population size groups for 1977 - 1983 NPTS are SMSA Size Groups and 1990 - 2001 are MSA Size Groups.

C In 2001, the mode “Bus” was divided into “Local Public Transit Bus,” “Commuter Bus,” “Charter/tour bus,” and “City to city bus.” Only “Local Public Transit

Bus” and “Commuter Bus” are included in public transit calculations.

C All modes includes other modes not specified such as bike, school bus, taxi and other.

C All tables reporting totals could include some unreported characteristics. Of particular interest, trips with an unreported mode dropped from 126 per household

in 1995 to 2 in 2001.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus, there are limits on the conclusions that

can be drawn in comparing travel with earlier survey years. The adjustments to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT)

and vehicle miles of travel (VMT).

C See Appendix for 2001 figures including 0 to 4 year-olds.
Household Travel 2001 NHTS Summary of Travel Trends (DRAFT)

18

Table 8

Person Trips per Household by Household Income

1983, 1990, and 1995 NPTS and 2001 NHTS

Income 1983 1990 1990 

Adjusted 1995 2001

Annual

Compounded

Rate,

1990-2001

ALL 2,628 2,673 3,262 3,828 3,581 0.9%

< $10,000 1,407 1,710 2,098 2,137 2,046 -0.2%

$10 to $20,000 1,927 1,968 2,412 2,790 2,542 0.5%

$20 to $30,000 2,376 2,455 3,008 3,522 3,065 0.2%

$30 to $40,000 2,739 2,802 3,431 3,980 3,535 0.3%

$40 to $50,000 3,037 3,101 3,791 4,298 3,905 0.3%

$50 to $60,000 3,284 3,391 4,138 4,539 4,348 0.5%

$60 to $70,000 3,485 3,660 4,458 4,726 4,545 0.2%

$70 to $80,000 3,635 3,832 4,659 4,855 4,867 0.4%

$80,000+ 3,602 3,747 4,570 4,829 4,934 0.7%

Unreported 2,090 2,536 3,424 2,431 -0.4%

Note:

C Incomes for 1983, 1990, adjusted 1990, and 1995 have been adjusted to 2001 dollars.

C All tables reporting totals could include some unreported characteristics.

C Note that only the 1990 person trip data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus, there are limits

on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments to 1990 data affect only person trips, vehicle

trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

C See Appendix for 2001 figures including 0 to 4 year-olds.

Since the NHTS sample excluded households without telephones, care should be taken in

interpreting results that might be affected by telephone ownership (which is related to family

income). For example, estimates of survey data categorized by family income could

underestimate trips made by low-income households and, therefore, not adequately represent the

population as a whole. Travel by more affluent households continued to grow, widening the gap

between low-income and high-income households.
2001 NHTS Summary of Travel Trends (DRAFT) Person Travel

19

Table 9

Total Person Trips by Mode of Transportation and Trip Purpose

Adjusted 1990 and 1995 NPTS, and 2001 NHTS

(millions)

Total To/ From

Work

WorkRelated

Business

Family/

Personal

Business

School or

Church

Social and

Recreational Other

Private

1990 Adj 267,029

(87.8%)

45,856

(91.2%)

3,178

(90.3%)

128,368

(92.7%)

17,545

(61.9%)

70,382

(86.3%)

1,629

(81.4%)

1995 327,400

(89.3%)

60,740

(92.8%)

8,835

(91.9%)

156,065

(92.6%)

22,436

(69.6%)

78,809

(87.6%)

470

(83.2%)

2001 331,791

(86.3%)

56,054

(92.4%)

10,648

(91.2%)

153,270

(90.9%)

26,861

(71.3%)

82,437

(80.7%)

2,147

(67.2%)

Public Transit

1990 Adj 5,460

(1.8%)

1,992

(4.0%)

92

(2.6%)

1,318

(1.0%)

1,076

(3.8%)

946

(1.2%)

35

(1.7%)

1995 6,638

(1.8%)

2,328

(3.6%)

123

(1.3%)

2,000

(1.2%)

826

(2.6%)

1,350

(1.5%)

11

(1.9%)

2001 6,202

(1.6%)

2,271

(3.7%)

213

(1.8%)

1,776

(1.1%)

800

(2.1%)

989

(1.0%)

134

(4.2%)

Walk

1990 Adj 21,879

(7.2%)

1,999

(4.0%)

154

(4.4%)

7,722

(5.6%)

3,649

(12.8%)

8,090

(9.9%)

265

(13.2%)

1995 20,325

(5.4%)

1,510

(2.3%)

240

(2.4%)

8,756

(5.0%)

2,925

(8.8%)

6,845

(7.3%)

47

(7.6%)

2001 33,145

(8.6%)

1,715

(2.8%)

487

(4.2%)

11,936

(7.1%)

3,630

(9.6%)

14,824

(14.5%)

507

(15.9%)

Other

1990 Adj 9,867

(3.2%)

428

(0.8%)

95

(2.7%)

1,087

(0.8%)

6,086

(21.4%)

2,098

(2.6%)

73

(3.6%)

1995 12,099

(3.2%)

887

(1.3%)

417

(4.2%)

1,768

(1.0%)

6,035

(18.1%)

2,954

(3.1%)

37

(6.0%)

2001 12.975

(3.4%)

584

(1.0%)

317

(2.7%)

1,468

(0.9%)

6,351

(16.9%)

3,829

(3.7%)

394

(12.3%)

TOTAL

1990 Adj 304,471

(100%)

50,314

(100%)

3,529

(100%)

138,559

(100%)

28,397

(100%)

81,575

(100%)

2,014

(100%)

1995 378,930

(100%)

66,901

(100%)

9,860

(100%)

173,764

(100%)

33,355

(100%)

94,362

(100%)

623

(100%)

2001 384,484

(100%)

60,690

(100%)

11,676

(100%)

168,560

(100%)

37,671

(100%)

102,165

(100%)

3,198

(100%)

Note:

C All tables reporting totals could include some unreported characteristics.

C 1995 VMT and vehicle trips with “To or From Work” as a trip purpose are believed to be overstated.

C Increases in Walk trips in 2001 are due, at least in part, to respondents being explicitly asked to include walk trips, which was not the case in prior surveys.

C In 2001, the mode “Bus” was divided into “Local Public Transit Bus,” “Commuter Bus,” “Charter/tour bus,” and “City to city bus.” Only “Local Public Transit Bus”

and “Commuter Bus” are included in public transit calculations.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus, there are limits on the conclusions that can be

drawn in comparing travel with earlier survey years. The adjustments to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle

miles of travel (VMT).

C See Appendix for 2001 figures including 0 to 4 year-olds.
Person Travel 2001 NHTS Summary of Travel Trends (DRAFT)

20

Table 10

Person Trips per Person by Trip Purpose and Gender

Adjusted 1990 and 1995 NPTS, and 2001 NHTS

Women Men

1990 Adj 1995 2001 1990 Adj 1995 2001

Total 1,401

(100%)

1,558

(100%)

1,494

(100%)

1,339

(100%)

1,579

(100%)

1,491

(100%)

To or From Work 197

(14.1%)

229

(14.7%)

200

(13.4%)

259

(19.3%)

327

(20.7%)

273

(18.3%)

Work Related Business 11

(0.8%)

23

(1.5%)

25

(1.7%)

21

(1.6%)

60

(3.8%)

66

(4.5%)

Family and Personal Business 693

(49.4%)

786

(50.5%)

715

(47.9%)

549

(41.0%)

648

(41.1%)

590

(39.6%)

School/Church 132

(9.4%)

141

(9.1%)

151

(10.1%)

123

(9.2%)

134

(8.5%)

141

(9.5%)

Social and Recreational 358

(25.6%)

375

(24.1%)

389

(26.0%)

377

(28.2%)

406

(25.7%)

405

(27.2%)

Other 9

(0.6%)

3

(0.2%)

12

(0.8%)

9

(0.7%)

2

(0.1%)

13

(0.9%)

Note:

C Note that 2001 data excludes persons aged 0 to 4 since travel by such persons were not included in the 1990 and 1995

surveys.

C 1995 VMT and vehicle trips with “To or From Work” as a trip purpose are believed to be overstated.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus,

there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments

to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

C All tables reporting totals could include some unreported characteristics.

Although both men and women took fewer trips, on average, in 2001 than in 1995, travel by

men decreased at a greater rate than that by women. By 2001, women were equally mobile as

men, in terms of the number of trips per person. Trips for family and personal business

continued to dominate women’s travel.
2001 NHTS Summary of Travel Trends (DRAFT) Person Travel

21

Figure 2

Distribution of Person Trips per Person by Gender and Trip Purpose

1995 NPTS and 2001 NHTS

The most striking gender difference in travel is non-work travel. About half of women’s travel

is for family and personal business (e.g., groceries shopping, taking children to school, or

organized sports.) The comparable rate for men is less than 40%. 
Person Travel 2001 NHTS Summary of Travel Trends (DRAFT)

22

Table 11 

Daily Trip Rates per Person by Trip Purpose

1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

1977 1983 1990 Adjusted 1990 1995 2001

Person Trips per Day

Total 2.92 2.89 3.08 3.76 4.30 4.09

To or From Work 0.57 0.59 0.62 0.62 0.76 0.65

Family/Personal Business 0.91 1.02 1.28 1.71 1.97 1.79

School/Church 0.35 0.34 0.35 0.35 0.38 0.40

Social and Recreational 0.71 0.80 0.76 1.01 1.07 1.09

Other 0.38 0.14 0.06 0.06 0.12 0.16

Person Miles of Travel per Day

Total 25.95 25.05 28.56 34.91 38.67 40.25

To or From Work 5.16 5.04 6.49 6.49 8.69 7.66

Family/Personal Business 5.68 6.46 8.93 12.10 13.51 13.20

School/Church 1.61 1.67 1.84 1.84 2.21 2.35

Social and Recreational 7.81 9.85 9.86 13.02 11.86 12.09

Other 5.68 2.04 1.43 1.46 2.39 4.80

Note:

C All tables reporting totals could include some unreported characteristics.

C Note that 2001 data excludes persons aged 0 to 4 since such persons were not included in the 1990 and 1995 surveys.

C The 1995 “To or From Work” person trips and person miles are believed to be overstated.

C “Other” trip purpose includes trips for work-related business.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus, there

are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments to 1990 data

affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

In 2001, a typical American household took fewer, but longer trips than in the previous years. 

On a per individual basis, the number of person trips per day decreased for the first time since

1977. This decrease might reflect the increase in the number of multi-person households which

reduced the need for members in the household to make the same type of trip. On average, a

person 5 years or older took about 4 trips a day, representing a 5% decrease from five years ago.

Almost one-half of these trips were for family and personal business.
2001 NHTS Summary of Travel Trends (DRAFT) Person Travel

23

Table 12

Distribution of Daily Person Miles of Travel per Person

by Mode of Transportation and Trip Purpose

Adjusted 1990 and 1995 NPTS, 2001 NHTS

Private Public Transit Other TOTAL

Adjusted

 1990 1995 2001

Adjusted

1990 1995 2001

Adjusted

1990 1995 2001

Adjusted

1990 1995 2001

TOTAL 30.85

(88.4%)

35.26

(92.1%)

35.49

(88.2%)

0.74

(2.1%)

0.82

(2.1%)

0.47

(1.2%)

3.31

(9.5%)

2.20

(5.7%)

4.10

(10.2%)

34.91

(100%)

38.67

(100%)

40.25

(100%)

To or From

 Work

6.15

(17.6%)

8.09

(20.9%)

7.11

(17.7%)

0.27

(0.8%)

0.30

(0.8%)

0.24

(0.6%)

0.06

(0.2%)

0.22

(0.6%)

0.30

(0.7%)

6.49

(18.6%)

8.69

(22.5%)

7.66

(19.0%)

Work Related

 Business

0.63

(1.8%)

1.85

(4.8%)

2.27

(5.6%)

0.01

(0.0%)

0.02

(0.1%)

0.01

(0.0%)

0.56

(1.6%)

0.34

(0.9%)

1.12

(2.8%)

1.20

(3.4%)

2.23

(5.8%)

3.41

(8.5%)

Family/Personal

 Business

11.39

(32.6%)

12.70

(32.8%)

12.77

(31.7%)

0.14

(0.4%)

0.19

(0.5%)

0.10

(0.3%)

0.57

(1.6%)

0.49

(1.3%)

0.32

(0.8%)

12.10

(34.7%)

13.51

(34.9%)

13.20

(32.8%)

School/

 Church 

1.32

(3.8%)

1.68

(4.3%)

1.87

(4.6%)

0.12

(0.3%)

0.07

(0.2%)

0.04

(0.1%)

0.40

(1.1%)

0.44

(1.1%)

0.44

(1.1%)

1.84

(5.3%)

2.21

(5.7%)

2.35

(5.8%)

Social and

 Recreational

11.12

(31.9%)

10.83

(28.0%)

11.01

(27.3%)

0.18

(0.5%)

0.24

(0.6%)

0.07

(0.2%)

1.71

(4.9%)

0.66

(1.7%)

1.01

(2.5%)

13.02

(37.3%)

11.86

(30.7%)

12.09

(30.0%)

Other 0.23

(0.7%)

0.10

(0.3%)

0.36

(0.9%)

0.01

(0.0%)

0.00

(0.0%)

0.00

(0.0%)

0.01

(0.0%)

0.05

(0.1%)

0.87

(2.2%)

0.25

(0.7%)

0.15

(0.4%)

1.39

(3.5%)

Note:

C All tables reporting totals could include some unreported characteristics.

C Note that 2001 data excludes persons aged 0 to 4 since such persons were not included in the 1990 and 1995

surveys.

C In 2001, the mode “Bus” was divided into “Local Public Transit Bus,” “Commuter Bus,” “Charter/tour bus,” and

“City to city bus.” Only “Local Public Transit Bus” and “Commuter Bus” are included in public transit

calculations.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. 

Thus, there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The

adjustments to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of

travel (VMT).

C Numbers in parenthesis are a percentage of total daily person miles of travel.

Although taking fewer trips, an individual traveled, on average, slightly more miles per day in

2001 than in 1995. The decreases in daily travel for work and for family and personal business

were offset somewhat by the increases in miles traveled for work-related business and for social

and recreational trips.
Person Travel 2001 NHTS Summary of Travel Trends (DRAFT)

24

Table 13

Average Daily Person Trips per Person by Age and Gender

1983, 1990, 1995 NPTS, and 2001 NHTS

Age

TOTAL Men Women

1983 1990 1990

Adj 1995 2001 1983 1990 1990

Adj 1995 2001 1983 1990 1990

Adj 1995 2001

Total 2.9 3.1 3.8 4.3 4.1 2.9 3.0 3.7 4.3 4.1 2.9 3.1 3.8 4.3 4.1

Under 16 2.3 2.6 3.1 3.7 3.4 2.3 2.6 3.0 3.7 3.5 2.3 2.6 3.1 3.8 3.4

16 to 20 3.3 3.5 4.2 4.6 4.1 3.2 3.5 4.2 4.6 4.0 3.4 3.5 4.2 4.7 4.2

21 to 35 3.5 3.6 4.4 4.6 4.3 3.4 3.5 4.2 4.5 4.2 3.5 3.7 4.6 4.8 4.5

36 to 65 2.9 3.2 3.9 4.6 4.5 2.9 3.1 3.7 4.6 4.4 3.0 3.3 4.1 4.6 4.5

Over 65 1.8 1.9 2.4 3.4 3.4 2.2 2.2 2.8 3.9 3.8 1.5 1.7 2.2 3.0 3.1

Note:

C All tables reporting totals could include some unreported characteristics.

C Note that 2001 data excludes persons aged 0 to 4 since such persons were not included in the 1990 and 1995

surveys.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. 

Thus, there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The

adjustments to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of

travel (VMT).
2001 NHTS Summary of Travel Trends (DRAFT) Person Travel

25

Figure 3

Average Daily Person Trips by Age and Gender

From 1995 to 2001

As a group, both men and women decreased their travel slightly from five years ago. By 2001,

men and women took, on average, an equal number of trips per day (Table 13). The most

striking gender difference in travel was among individuals 65 years or older. Women 65 years

or older took about 20% fewer trips than did older men. Between the ages 16 and 65, women

took an equal number or more trips than men. This pattern was true for both 1995 and 2001.
Person Travel 2001 NHTS Summary of Travel Trends (DRAFT)

26

Table 14

Average Daily Person Miles of Travel per Person by Age and Gender

1983, 1990, 1995 NPTS, and 2001 NHTS

Age

TOTAL Men Women

1983 1990 1990

Adj 1995 2001 1983 1990 1990

Adj 1995 2001 1983 1990 1990

Adj 1995 2001

Total 25.1 28.6 34.9 38.7 40.2 27.7 31.6 38.0 43.9 45.0 22.6 25.8 32.1 33.8 35.7

Under 16 16.2 16.2 20.1 25.0 24.5 16.8 16.3 20.3 23.7 24.6 15.4 16.1 19.9 26.2 24.4

16 to 20 22.2 28.1 34.4 36.4 38.1 23.0 30.1 36.9 37.6 34.1 21.5 26.2 32.2 35.0 42.5

21 to 35 31.1 36.5 44.3 46.0 45.6 32.8 40.4 48.2 51.3 49.8 29.5 32.9 40.7 40.8 41.5

36 to 65 29.2 33.0 40.1 45.1 48.8 33.6 36.5 43.4 53.2 57.7 25.2 29.7 37.0 37.5 40.4

Over 65 12.0 14.2 18.4 24.4 27.5 14.8 17.4 22.5 31.7 32.9 10.2 11.8 15.3 19.2 23.5

Note:

C All tables reporting totals could include some unreported characteristics.

C Note that 2001 data excludes persons aged 0 to 4 since such persons were not included in the 1990 and 1995

surveys.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. 

Thus, there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The

adjustments to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of

travel (VMT).

On average, an individual traveled 40 miles per day, with men traveling 10 miles more, on

average, than women. As evident in Table 14 and Figure 4, there were significant travel

differences between men and women by age. The difference in miles traveled is particularly

telling given the fact that men and women took about an equal number of trips per day (Table

13). Women's trips were notably shorter than men's trips. 
2001 NHTS Summary of Travel Trends (DRAFT) Person Travel

27

Figure 4

Average Daily Person Miles of Travel per Person by Gender

1995 NPTS and 2001 NHTS
Person Travel 2001 NHTS Summary of Travel Trends (DRAFT)

28

Figure 5.

Average Time Spent in Vehicle (Minutes) by Age

2001 NHTS

The average amount of time we spent in a vehicle (as a driver or a passenger) in 2001 was

slightly more than an hour and varied greatly by an individual’s age. Children younger than 5

years old spent three-quarters of an hour a day in vehicles. Compared to 1995, Americans spent

about 10% more time in their vehicles but traveled about the same number of miles (Figure 6).
2001 NHTS Summary of Travel Trends (DRAFT) Person Travel

29

Figure 6

Average Time Spent in Vehicle and Miles Traveled

1995 NPTS and 2001 NHTS
Private Vehicle Travel 2001 NHTS Summary of Travel Trends (DRAFT)

30

Table 15

Average Time Spent Driving a Private Vehicle in a Typical Day by MSA Size

Adjusted 1990 and 1995 NPTS, and 2001 NHTS

 (in Minutes)

All Drivers Only Persons Who Drove 

on Their Travel Day

MSA Size 1990 Adj 1995 2001 1990 Adj 1995 2001

ALL 49.35 56.20 61.23 71.88 73.07 81.35

Not in MSA 48.85 56.36 60.87 69.20 72.75 81.74

< 250,000 48.36 53.86 59.21 67.94 69.14 76.40

250,000 to 499,999 47.82 55.81 58.71 71.66 71.49 76.50

500,000 to 999,999 50.20 56.76 61.70 72.42 73.12 79.34

1 to 2.9 million 50.61 56.48 61.62 74.38 72.13 79.55

3+ million 49.38 56.43 62.13 71.08 74.86 85.12

Note:

C For 1990 and 1995, average time spent driving does not include any driving done in a segmented trip. Also excludes

driving done as an "essential part of work."

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus,

there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments

to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

The average time spent driving a private vehicle was calculated using two different methods:

1) by including all drivers, even those who did not drive a private vehicle on the designated

travel day, and 2) by excluding any drivers who did not drive on the designated travel day. Note

the 1990 data reported here are different from those published in the 1990 Nationwide Personal

Transportation Survey Databook, Volume II (Tables 5-66 to 5-68), due to the fact that adjusted

data were used for 1990. In 2001, a driver spent on average more than one hour behind the

wheel, an increase of 6 minutes from 1995. People living in smaller cities generally spent

slightly less time driving than those living in large areas.
2001 NHTS Summary of Travel Trends (DRAFT) Private Vehicle Travel

31

Table 16

Average Vehicle Occupancy for Selected Trip Purposes

1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

(person miles per vehicle mile)

Trip Purpose

1977 1983 1990 1995 2001

Percent Change (77-

01)

Total Change

To or From Work 1.3 1.29 1.14 1.14 1.14 -12.31%

Shopping 2.1 1.79 1.71 1.74 1.79 -14.76%

Other Family or

 Personal Business 2.0 1.81 1.84 1.78 1.83 -8.50%

Social and Recreational 2.4 2.12 2.08 2.04 2.03 -15.42%

All Purposes 1.9 1.75 1.64 1.59 1.63 -14.21%

Note:

C All Purposes includes other trip purposes not shown, such as trips to school, church, doctor, dentist, and 

work-related business trips.

The trend of declining average vehicle occupancy, measured as person miles per vehicle mile,

was reversed in 2001. The difference between 1995 and 2001 is statistically significant at 95%

confidence. This trend probably reflects the gasoline price increases. In general, people are

less likely to carpool for commutes to and from work, but more likely to share rides for social

and recreational trips. 
Vehicle Availability and Utilization 2001 NHTS Summary of Travel Trends (DRAFT)

32

Table 17

Availability of Household Vehicles

1969, 1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

(thousands)

Households with -- 1969 1977 1983 1990 1995 2001

No Vehicle 12,876

(20.6%)

11,538

(15.3%)

11,548

(13.5%)

8,573

(9.2%)

7,989

(8.1%)

8,716

(8.1%)

One Vehicle 30,252

(48.4%)

26,092

(34.6%)

28,780

(33.7%)

30,654

(32.8%)

32,064

(32.4%)

33,757

(31.4%)

Two Vehicles 16,501

(26.4%)

25,942

(34.4%)

28,632

(33.5%)

35,872

(38.4%)

40,024

(40.4%)

39,938

(37.2%)

Three or More

Vehicles

2,875

(4.6%)

11,840

(15.7%)

16,411

(19.2%)

18,248

(19.6%)

18,914

(19.1%)

24,955

(23.2%)

ALL 62,504

(100.0%)

75,412

(100.0%)

85,371

(100.0%)

93,347

(100.0%)

98,990

(100.0%)

107,365

(100.0%)

Vehicles Per

Household 1.16 1.59 1.68 1.77 1.78 1.89

Note:

C The 1969 survey does not include pickups or other light trucks as household vehicles.

More than 60% of all households had 2 or more vehicles in 2001. Furthermore, not only were

there more multi-vehicle households in 2001 than in 1995, they also owned more vehicles.

There was a shift in 2001 from 1- to 2-vehicle households to 3+ vehicle households.

Households that owned at least one vehicle owned an average of 2.05 vehicles in 2001,

compared to 1.93 in 1995. The percentage of households without a vehicle remained at the

1995 level, though the number of households without a vehicle increased - from 8 million

households in 1995 to more than 8.7 million in 2001. 
2001 NHTS Summary of Travel Trends (DRAFT) Vehicle Availability and Utilization

2 Only includes households that reported income information.

33

Figure 7

Household Distribution2 by Household Income and Vehicle to Driver Ratio

2001 NHTS

There were significantly more households in 2001 than in 1995 who owned a greater number

of vehicles than there were drivers in the household. More than eighty percent of the

households had at least one vehicle for each of their drivers in 2001. It is clear that income

affects vehicle ownership and availability. Three out of every four low-income families did not

own a vehicle, while one in two families with household income more than $55,000 had more

vehicles than licensed drivers in their households. 
Vehicle Availability and Utilization 2001 NHTS Summary of Travel Trends (DRAFT)

34

Table 18

Distribution of Households by Household Vehicle Availability and Population Density

1990 and 1995 NPTS and 2001 NHTS

Household Vehicle

Availability

Population Density (Persons per Square Mile)

Less than 2,000 2,000 to 4,000 4,000 to 10,000 10,000 or more

1990 1995 2001 1990 1995 2001 1990 1995 2001 1990 1995 2001

ALL 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%

No Vehicle 6.1% 3.9% 4.2% 7.6% 6.2% 5.9% 10.9% 8.5% 8.7% 35.1% 31.0% 28.1%

One Vehicle 30.4% 27.3% 26.2% 33.4% 33.8% 34.1% 38.2% 38.6% 37.0% 40.0% 41.7% 39.9%

Two Vehicles 41.0% 44.5% 40.1% 41.5% 42.3% 38.6% 34.9% 38.6% 36.5% 18.4% 21.3% 23.1%

Three or More

Vehicles 22.5% 24.3% 29.5% 17.5% 17.7% 21.4% 16.0% 14.4% 17.7% 6.5% 6.0% 8.9%

Population density seems to have little or no impact on households’ decisions to own a vehicle,

except in highly-populated areas with more than ten thousand persons per square mile. Almost

thirty percent of the households in areas with a population density greater than 10,000 per square

mile did not own a vehicle. On the other hand, almost 70% of the households in the least

densely-populated areas owned more than two vehicles.
2001 NHTS Summary of Travel Trends (DRAFT) Vehicle Availability and Utilization

35

Figure 8

Vehicle Ownership and Demographic Statistics by Population Density

2001 NHTS
Vehicle Availability and Utilization 2001 NHTS Summary of Travel Trends (DRAFT)

36

Table 19

Percent of Households Without a Vehicle Within MSA Size Group

1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

(S)MSA Size

% Households Within An Area Without a Vehicle

1977 1983 1990 1995 2001 % Change

1977-2001

Not in (S)MSA 12.2 10.5 7.7 5.3 5.8 -52%

< 250,000 13.7 10.1 8.6 4.8 5.8 -58%

250,000 to 499,999 12.2 8.1 5.7 7.3 5.2 -57%

500,000 to 999,999 14.0 14.3 8.4 6.3 7.0 -50%

1 to 2.9 million 14.2 12.1 8.2 6.9 6.4 -55%

3+ million 26.1 25.4 12.4 11.2 11.9 -54%

ALL 15.3 13.5 9.2 8.1 8.1 -47%

Note:

C The population size groups for 1977 - 1983 NPTS are SMSA Size Groups and 1990 - 2001 are MSA Size Groups.

C All tables reporting totals could include some unreported characteristics.

The percentage of households not owning a vehicle increases with increasing area size. In

2001, about 6% of the households in non-MSA areas or in small cities (< 250,000) were without

a vehicle, representing a slight increase from 1995. The comparable percentage for areas with

more than 3 million people was close to 12%. In large cities, such as New York, some zerovehicle households are by choice due to the high cost and the inconvenience of owning a

vehicle, and the availability of other modes. About 6 to 7 percent of the households in mediumsize cities (with 500,000 to 3 million people) did not have a vehicle.
2001 NHTS Summary of Travel Trends (DRAFT) Vehicle Availability and Utilization

37

Table 20

Vehicle Distribution and Average Vehicle Age by Vehicle Type

1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

1977 1983 1990 1995 2001

Distribution of Vehicles

 TOTAL 100.0 100.0 100.0 100.0 100.0

 Auto 79.6 75.9 74.7 64.3 56.8

 Van 2.8 3.6 5.5 7.8 9.0

 Sport Utility NA NA NA 6.9 12.1

 Pickup 12.8 15.2 17.2 17.7 18.4

 Other Truck 1.3 1.5 0.6 0.4 0.5

 RV/Motor Home 0.4 0.5 0.5 0.5 0.7

 Motorcycle 2.7 2.5 1.3 0.9 2.1

 Moped 0.2 0.6 0.1 NA NA

 Other 0.2 0.2 0.1 0.1 0.5

Average Vehicle Age

 TOTAL 6.6 7.60 7.71 8.33 8.87

 Auto 6.4 7.20 7.61 8.24 8.98

 Van 5.5 8.45 5.88 6.68 7.56

 Sport Utility NA NA NA 6.56 6.44

 Pickup 7.3 8.54 8.43 9.65 10.05

 Other Truck 11.6 12.39 14.48 14.93 17.72

 RV/Motor Home 4.5 10.69 10.44 13.21 13.49

Note:

C The 1977, 1983, and 1990 surveys do not include a separate category for sports utility vehicles, while

the 1995 and 2001 surveys do. In 1990 survey, most SUVs were classified as automobiles. The 1995

and 2001 surveys do not include a separate category for mopeds.

C Motorcycle, moped, and other pov are excluded from the calculation of vehicle age.

C All tables reporting totals could include some unreported characteristics.

Automobiles continued to lose their market share of private vehicles, from 80% in 1977 to less

than 60% in 2001. In the meantime, the market share for sport utility vehicles (SUVs) doubled

between 1995 and 2001. Except for SUVs, the average age of vehicles in 2001 was greater

than in the past.
Vehicle Availability and Utilization 2001 NHTS Summary of Travel Trends (DRAFT)

38

Table 21

Distribution of Vehicles by Vehicle Age and Vehicle Type

1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

(percentage)

1977 1983 1990 1995 2001

Vehicle Age Auto Truck/

Van

All Auto Truck/

Van

All Auto Truck/

Van

All Auto Truck/

Van

All Auto Truck/

Van

All

0 to 2 years 27.3 29.9 27.8 20.0 16.6 19.2 15.6 19.7 16.6 14.9 19.2 16.2 13.27 18.59 15.41

3 to 5 years 30.4 25.6 29.6 28.0 26.6 27.6 27.7 27.2 27.5 21.7 21.6 21.5 20.37 23.47 21.51

6 to 9 years 26.7 21.1 25.7 27.4 25.0 26.9 26.8 20.9 25.3 30.3 25.5 28.5 25.45 22.59 24.08

10 or more

 years 15.6 23.4 16.9 24.6 31.8 26.3 29.9 32.2 30.6 33.1 33.7 33.8 40.91 35.36 39.00

Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

Average Age 5.5 6.4 5.6 6.7 7.8 6.9 7.6 8.0 7.7 8.2 8.3 8.3 9.0 8.5 8.9

Note:

C The 1969 survey does not include pickups and other light trucks as household vehicles.

C Totals do not include any unreported vehicle ages, but do include vehicle types such as motorcycle, RV, etc. that are

not shown.

In 2001, household vehicles remained in operation significantly longer than those in 1977. In

1977, automobiles averaged 5.5 years of age while automobiles in 2001 averaged 9 years of age

– an increase of almost 3.5 years. In 2001, two out of every five vehicles were at least 10 years

old. In the past, trucks and vans tended to be in operation longer than automobiles. However,

this trend was no longer true by 2001.
2001 NHTS Summary of Travel Trends (DRAFT) Vehicle Availability and Utilization

39

Figure 9

Distribution of Vehicles by Vehicle Age

1977, 1983, 1990 and 1995 NPTS and 2001 NHTS
Vehicle Availability and Utilization 2001 NHTS Summary of Travel Trends (DRAFT)

40

Table 22

Average Annual Miles per Vehicle by Vehicle Age

(Vehicle Owner’s Estimate)

1969, 1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

Percent Change 

Annual 

Rate

Total

Change

 Vehicle Age 1969 1977 1983 1990 1995 2001 69-01 69-01

 0 to 2 years 15,700 14,460 15,292 16,811 16,092 14,892 -0.16% -5.15%

 3 to 5 years 11,200 11,074 11,902 13,706 14,004 13,230 0.52% 18.13%

 6 to 9 years 9,700 9,199 9,253 12,554 12,608 11,603 0.56% 19.62%

 10 or more years 6,500 6,755 7,023 9,176 8,758 7,863 0.60% 20.97%

 ALL 11,600 10,679 10,315 12,458 12,226 11,078 -0.14% -4.50%

Note:

C The 1969 survey does not include pickups and other light trucks as household vehicles.

C All tables reporting totals could include some unreported characteristics.

Based on vehicle owners’ estimates, a vehicle was driven, on average, slightly more than

11,000 miles a year in 2001, a decrease of 9% from 1995. Regardless of vehicle age, vehicles

were driven less in 2001, on average, than in 1995 or in 1990. Given the trend of more than

one vehicle per licensed driver, it is plausible that individual vehicles are being driven less than

in previous years. 
2001 NHTS Summary of Travel Trends (DRAFT) Vehicle Availability and Utilization

41

Table 23

Average Annual Miles per Licensed Driver by Driver Age and Gender

(Driver’s Self Estimate)

1969, 1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

Driver Age 1969 1977 1983 1990 1995 2001

Percent Change 

Annual Rate Total Change

69-01 69-01

 ALL

16 to 19 4,633 5,662 4,986 8,485 7,624 7,331 1.44% 58.23%

20 to 34 9,348 11,063 11,531 14,776 15,098 15,650 1.62% 67.42%

35 to 54 9,771 11,539 12,627 14,836 15,291 15,627 1.48% 59.93%

55 to 64 8,611 9,196 9,611 11,436 11,972 13,177 1.34% 53.03%

65+ 5,171 5,475 5,386 7,084 7,646 7,684 1.25% 48.60%

ALL 8,685 10,006 10,536 13,125 13,476 13,785 1.45% 58.72%

 Men

16 to 19 5,461 7,045 5,908 9,543 8,206 8,228 1.29% 50.67%

20 to 34 13,133 15,222 15,844 18,310 17,976 18,634 1.10% 41.89%

35 to 54 12,841 16,097 17,808 18,871 18,858 19,287 1.28% 50.20%

55 to 64 10,696 12,455 13,431 15,224 15,859 16,883 1.44% 57.84%

65+ 5,919 6,795 7,198 9,162 10,304 10,163 1.70% 71.70%

ALL 11,352 13,397 13,962 16,536 16,550 16,920 1.26% 49.05%

 Women

16 to 19 3,586 4,036 3,874 7,387 6,873 6,106 1.68% 70.27%

20 to 34 5,512 6,571 7,121 11,174 12,004 12,266 2.53% 122.53%

35 to 54 6,003 6,534 7,347 10,539 11,464 11,590 2.08% 93.07%

55 to 64 5,375 5,097 5,432 7,211 7,780 8,795 1.55% 63.63%

65+ 3,664 3,572 3,308 4,750 4,785 4,803 0.85% 31.09%

ALL 5,411 5,940 6,382 9,528 10,142 10,233 2.01% 89.11%

Note:

C All tables reporting totals could include some unreported characteristics.

C In 1995, some drivers indicating that they drove 'no miles' for their average annual miles were changed to 'miles not reported.' 

The number of miles driven per licensed driver continued to increase. On average, drivers in

2001 drove 3,000 miles more per year than those in 1995. This increase was primarily due to

the increased driving in 2001 by drivers between 55 and 65 years old compared to the amount

of driving by those of similar ages in 1995. The level of teen driving by girls decreased

significantly from the 1995 level. 
Commute Travel Patterns 2001 NHTS Summary of Travel Trends (DRAFT)

42

Table 24

Commute VMT and Total VMT By Year

1969, 1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

1969 1977 1983 1990 1990 adj 1995 2001

Commute Vehicle Trips

 (000,000) 27,844 31,886 35,271 41,792 41,792 54,782 51,395

Commute VMT (000,000) 260,716 287,710 301,644 453,042 453,042 642,610 614,548

Total VMT (000,000) 775,940 907,603 1,002,139 1,409,600 1,695,290 2,068,368 2,274,797

% Commute VMT of Total

 VMT 33.60% 31.70% 30.10% 32.14% 26.72% 31.07% 27.02%

Workers (000) 75,758 93,019 103,244 118,343 118,343 131,697 145,272

Annual Commute Vehicle

Trips per Worker 368 343 342 353 353 416 354

Note:

C 1995 VMT and vehicle trips with “To or From Work” as a trip purpose are believed to be overstated.

C Caution should be used when comparing the number of workers or the number of commute trips between the

1990 and 1995 NPTS. Slightly different approaches were used in defining workers and commute trips between

the 1990 and 1995 NPTS.
2001 NHTS Summary of Travel Trends (DRAFT) Commute Travel Patterns

43

Figure 10

Distribution of Workers by Usual Mode

1995 NPTS and 2001 NHTS

(percentage)

 

 
Commute Travel Patterns 2001 NHTS Summary of Travel Trends (DRAFT)

44

 

Table 25

Distribution of Workers by Usual Mode

1969, 1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

(percentage)

Mode of Transportation 1969 1977 1983 1990 1995 2001

All Modes 100.0 100.0 100.0 100.0 100.0 100.0

Auto, Truck, Van, or Utility Vehicle 90.8 87.0 88.6 87.8 91.0 90.8

Public Transit 8.4 6.0 5.3 5.3 5.1 5.1

Walk N/A 4.1 4.3 4.0 2.6 2.8

Other 0.8 2.9 1.8 2.9 1.3 1.3

Note:

C Usual mode is defined as the means of transportation usually used to go to work during the week before the

interview. Data in this table are derived from the person file.

C The 1969 survey excludes walk trips.

C All modes does not include workers who worked at home or any unreported modes.

C Other includes other modes not shown above such as RV, motorcycle, other POV, Amtrak, airplane, taxi, bike,

school bus, and other.

Workers in the U.S. predominately traveled to work in privately-owned vehicles. About 5%

of the commuters reported public transit as their usual mode to work. This percentage has

remained at about this level since 1983. 
2001 NHTS Summary of Travel Trends (DRAFT) Commute Travel Patterns

45

Table 26

General Commute Patterns by Mode of Transportation

1983, 1990, 1995 NPTS, and 2001 NHTS

1983 1990 1995 2001 1983 1990 1995 2001 1983 1990 1995 2001 1983 1990 1995 2001

ALL MODES Private Public Transit Walk

Average Commute Trip Length (miles)

8.54 10.65 11.63 12.11 8.86 11.02 11.84 12.10 11.81 12.75 12.88 11.73 0.32 0.83 0.74 0.91

Average Commute Travel Time (minutes)

18.20 19.60 20.65 23.32 17.62 19.05 20.10 22.49 39.77 41.10 41.95 47.89 8.58 9.79 10.86 14.06

Average Commute Speed (miles per hour)

28.28 33.35 34.67 32.23 30.28 34.70 35.18 32.27 17.96 17.90 19.57 - 2.21 3.25 3.58 3.18

Note:

C All Public Transit trips in 2001 had an access or egress recorded, which is equivalent to a 1990 or 1995

segmented trip. For this reason, average commute speed for these trips was not computed, and average

commute travel time information may not be comparable to that of previous years.

C All trip miles and travel times were calculated using actual trips to and from work as reported in the travel day file.

C Average Commute Speed was calculated using only those trips with both trip mileage and travel time information

present.

C Average commute trip length for 1990, 1995, and 2001 was calculated using only those records with trip mileage

information present.

C Average commute travel time does not include time spent waiting for transportation. In the 2001 NHTS, this

involved subtracting the number of minutes waiting for public transit (TRWAITTM) from the number of minutes

to complete entire trip (TRVL_MIN).

C Average commute speed for 1990 and 1995 NPTS does not include any segmented trips because a change in the

mode of transportation during the trip would cause the calculation of average commute speed to be meaningless.

C In 2001, the mode “Bus” was divided into “Local Public Transit Bus,” “Commuter Bus,” “Charter/tour bus,” and

“City to city bus.” Only “Local Public Transit Bus” and “Commuter Bus” are included in public transit calculations.

C All tables reporting totals could include some unreported characteristics. Air, taxi, bicycle, school bus, “Other”, and

unreported vehicle types are excluded from the listed categories but included in “ALL MODES” totals for all years.

From 1990, Amtrak is also included in totals but excluded from listed categories. In 2001, several new vehicle

definitions are also omitted from listed categories but included in totals: charter bus, city to city bus, ship/cruise,

passenger line/ferry, sailboat/motorboat/yacht, limousine, and hotel/airport shuttle.
Commute Travel Patterns 2001 NHTS Summary of Travel Trends (DRAFT)

46

Figure 11

Average Commute Time in Privately-Owned Vehicles and MSA Size

1995 NPTS and 2001 NHTS

The average distance for commutes in privately-owned vehicles has remained relatively constant

since 1995. However, the average commute time increased by more than 10% from 1995 to

2001, reflecting slower commute speeds and greater congestion (Tables 26 and 27). This was

true regardless of where people lived (Figure 11). Compared to 1995, the commute distances

by public transit in 2001were shorter, but took more time.
2001 NHTS Summary of Travel Trends (DRAFT) Commute Travel Patterns

47

Table 27

Average Commute Speed by MSA Size

1983, 1990, 1995 NPTS, and 2001 NHTS

(miles per hour)

MSA Size

Not in

(S)MSA

Less than

250,000

250,000 to

499,999

500,000 to

999,999

1 to 2.9

million

3 million and

over

POV

1983 33.44 28.28 30.14 29.91 30.00 28.37

1990 39.07 34.39 34.77 35.60 33.33 32.81

1995 39.53 36.55 35.21 35.36 34.11 33.43

2001 38.18 33.31 32.02 33.45 31.22 29.69

ALL MODES (INCLUDING POV)

1983 32.23 27.26 30.08 28.52 28.09 24.51

1990 37.82 33.66 34.14 34.60 32.35 30.92

1995 38.90 35.85 35.98 35.25 34.62 32.41

2001 37.69 32.78 31.46 33.70 30.84 30.24

Note:

• Average Commute Speed is calculated using only those trips with both trip mileage and travel time information

present

• All trip miles and travel times were calculated using actual trips to and from work as reported in the travel day file.

• Average commute speed for 1990 and 1995 NPTS does not include any segmented trips because a change in the

mode of transportation during the trip would cause the calculation of average commute speed to be meaningless.

• Trips involving an access to or egress from public transit in 2001 were excluded.

• The population size groups for 1977 - 1983 NPTS are SMSA Size Groups and 1990 - 2001 are MSA Size Groups.
Commute Travel Patterns 2001 NHTS Summary of Travel Trends (DRAFT)

48

Not a MSA

500,000-999,999 people

1 - 2.9 million people

< 250,000 people

250,000-499,999 people

> 3 million people

Figure 12

Average Commute Speed for Selected Time of Day by MSA Size

2001 NHTS

(miles per hour)

In almost all areas, average commute speeds have decreased since 1995 (Table 27). Generally,

as the population of an area increases, commute speeds decrease. Depending on the time of day

and location, average commute speeds ranged widely. In larger areas, commute speeds start

to decline in mid-afternoon and continue to decline well into the early evening. 
2001 NHTS Summary of Travel Trends (DRAFT) Temporal Distribution

49

Table 28

Distribution of Person Trips by Start Time of Trip

1983, 1990, 1995 NPTS, and 2001 NHTS

Time of Day 1983 1990 1990

 Adj 1995 2001

 10 pm - 1 am 4.0 4.0 4.1 3.5 2.9

 1 - 6 am 3.3 1.9 1.8 1.7 1.8

 6 - 9 am 14.4 13.9 12.5 13.8 14.4

 9 am - 1 pm 23.4 20.1 20.6 24.2 24.6

 1 - 4 pm 20.8 20.4 20.7 22.1 22.1

 4 - 7 pm 21.2 22.8 22.9 23.0 22.3

 7 - 10 pm 12.3 12.8 13.2 11.8 11.7

 ALL 100.0 100.0 100.0 100.0 100.0

Note:

• All tables reporting totals could include some unreported characteristics.

• Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus,

there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments

to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

• See Appendix for 2001 figures including 0 to 4 year-olds.

The temporal distribution of personal trips remained the same during the past decade – more

than two-fifths of the trips started between 9 o’clock in the morning and 4 o’clock in the

afternoon. However, this distribution varies somewhat by trip purpose (see Figure 13). As

expected, commuting to and from work began predominately between 6 and 9 o’clock in the

morning and between 4 and 7 o’clock in the afternoon while more than half of work-related

trips started between 9 am and 4 pm.
Temporal Distribution 2001 NHTS Summary of Travel Trends (DRAFT)

50

Figure 13

Distribution of Person Trips by Trip Purpose and Start Time of Trip

2001 NHTS
2001 NHTS Summary of Travel Trends (DRAFT) Temporal Distribution

51

Table 29

Daily Travel Statistics by Weekday vs Weekend

Adjusted 1990, 1995 NPTS, and 2001 NHTS

Daily Travel Statistics 1990 Adjusted 1995 2001

Weekday Weekend Weekday Weekend Weekday Weekend

Vehicle Trips per Driver 3.41 2.89 3.81 2.99 3.56 2.85

% work trips 27.8% 9.7% 31.9% 12.5% 31.2% 10.6%

% non-work trips 72.2% 90.3% 68.1% 87.5% 68.8% 89.4%

VMT per Driver 28.54 28.36 33.46 28.87 34.35 28.70

Average Vehicle Trip

Length

8.47 9.96 8.85 9.73 9.75 10.22

Average Time Spent

Driving (in minutes)

50.68 46.07 59.48 48.05 64.79 52.39

Person Trips per Person 3.82 3.60 4.43 3.96 4.18 3.86

PMT per Person 32.6 40.64 37.68 41.14 39.41 42.31

Average Person Trip

Length

9.47 11.51 8.63 10.53 9.60 11.18

Note:

• Average time spent driving includes all drivers, even those who did not drive a private vehicle on the day in which

the household was interviewed. It does not include any driving done in a segmented trip. Also excludes driving done

as an "essential part of work."

• Average trip length is calculated using only those records with trip mileage information present.

• Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus,

there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments

to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

• For Tables 28 and 29, “% Work Trips” also includes Work-Related Business

Although travel was less frequent on weekends than on weekdays, weekend trips were on average

longer than weekday trips. This has been true since 1990. Compared to 1995, the average time

spent driving in 2001 was longer regardless of weekdays or weekends.
Travel Behavior of Sub-Populations 2001 NHTS Summary of Travel Trends (DRAFT)

52

Table 30

Daily Travel Statistics of People 65 and Older

1983, 1990, 1995 NPTS, and 2001 NHTS

Daily Travel Statistics 1983 1990 1990

Adjusted

1995 2001

Vehicle Trips per Driver 1.66 1.78 2.27 2.94 2.84

% work trips 10.2% 6.2% 4.8% 8.5% 6.2%

% non-work trips 89.8% 93.8% 95.2% 91.5% 93.8%

VMT per Driver 9.80 11.50 14.83 19.56 21.13

Average Vehicle Trip Length 5.92 6.55 6.61 6.69 7.51

Average Time Spent Driving

(in minutes)

NA 24.02 30.83 42.89 49.11

Person Trips per Person 1.82 1.95 2.49 3.43 3.42

PMT per Person 12.21 15.33 19.85 25.24 28.04

Average Person Trip Length 6.70 7.99 8.12 7.46 8.35

Note:

C Average time spent driving includes all drivers, even those who did not drive a private vehicle on the day in which

the household was interviewed. It does not include any driving done in a segmented trip. Also excludes driving done

as an "essential part of work."

C Average trip length is calculated using only those records with trip mileage information present.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus,

there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments

to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

C For Tables 29 and 30, “% Work Trips” also includes Work-Related Business.

On a daily basis, individuals 65 and older took fewer but longer trips in 2001 than in 1995. On

average, an elderly driver spent almost fifty minutes a day behind the wheel, representing an

increase of 14% from 1995. Work trips became less common in 2001.
2001 NHTS Summary of Travel Trends (DRAFT) Travel Behavior of Sub-Populations

53

Table 31

Daily Person Trips of Adult Women by Household Composition

1983, 1990, 1995 NPTS, and 2001 NHTS

Household Composition 1983 1990 Adjusted

1990 1995 2001

 ALL 2.95 3.23 4.00 4.36 4.25

% work trips 17.6% 17.7% 14.3% 15.8% 17.8%

 Single Adult, No Child 2.60 3.32 4.07 4.19 4.26

 2 or > Adult, No Child 2.85 3.29 4.01 4.19 4.15

 Single Adult, Child<6 2.65 3.59 4.48 4.80 4.68

 2 or > Adult, Child<6 3.32 3.51 4.41 4.74 4.55

 Single Adult, Child 6-15 3.73 4.17 5.17 5.35 5.18

 2 or > Adult, Child 6-15 3.59 3.85 4.78 5.24 4.87

 Single Adult, Child 16-21 2.59 3.41 4.17 4.56 4.67

 2 or > Adult, Child 16-21 2.84 3.40 4.13 4.54 4.43

 Single Adult, Retired 1.49 1.79 2.30 3.06 3.26

 2 or > Adult, Retired 1.97 2.17 2.75 3.48 3.50

Note:

C All tables reporting totals could include some unreported characteristics.

C In 1983, adult women were defined as all females 16 or older. In 1990, 1995, and 2001, adult women were defined

as females 18 or older.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus,

there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments

to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

Regardless of household demographic composition, women took more trips in 1995 than in 2001.

Single women with children between the ages 6 and 15 averaged more than 5 trips per day. The

proportion of work trips women took increased two percentage points from 1995 to 2001. 
Travel Behavior of Sub-Populations 2001 NHTS Summary of Travel Trends (DRAFT)

54

Table 32

Daily Person Trips per Person for Low Income Households by Trip Purpose

1983, 1990, and 1995 NPTS

Trip Purpose

Low-Income Households

(Less than $25,000 of 2001 dollars)

Other

Households

1983 1990 Adjusted

1990 1995 2001 1995 2001

ALL 2.44

(100.0%)

2.77

(100.0%)

3.40

(100.0%)

3.79

(100.0%)

3.52

(100.0%)

4.57

(100.0%)

4.32

(100.0%)

To/From Work 0.46

(18.7%)

0.48

(17.5%)

0.49

(14.3%)

0.57

(15.1%)

0.46

(13.0%)

0.85

(18.7%)

0.72

(16.6%)

Work Related Business 0.06

(2.4%)

0.02

(0.9%)

0.03

(0.8%)

0.06

(1.6%)

0.07

(2.1%)

0.14

(3.0%)

0.14

(3.3%)

Family/Personal Business 0.89

(36.3%)

1.20

(43.3%)

1.60

(47.1%)

1.84

(48.5%)

1.67

(47.3%)

2.05

(44.8%)

1.86

(42.9%)

School/Church 0.29

(12.0%)

0.35

(12.6%)

0.35

(10.3%)

0.35

(9.3%)

0.41

(11.5%)

0.39

(8.5%)

0.41

(9.3%)

Social & Recreational 0.69

(28.2%)

0.69

(24.9%)

0.91

(26.8%)

0.96

(25.3%)

0.89

(25.3%)

1.13

(24.7%)

1.16

(26.8%)

Other 0.06

(2.4%)

0.02

(0.8%)

0.02

(0.7%)

0.00

(0.1%)

0.02

(0.7%)

0.01

(0.2%)

0.04

(0.9%)

Note:

C Incomes for 1983, 1990, and 1995 have been adjusted to 2001 dollars.

C Low income households are defined as a household earning $25,000 or less in a year.

C All tables reporting totals could include some unreported characteristics.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus,

there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments

to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).

Similar to those in higher income households, individuals with low income took fewer trips in

2001 than in 1995. However, individuals in low-income households continued to be less mobile

and took fewer trips to, or related to, work when compared to those in higher income

households.
2001 NHTS Summary of Travel Trends (DRAFT) Travel Behavior of Sub-Populations

55

Table 33

Daily Person Trips per Person

by Vehicle Ownership Status and MSA Size

Adjusted 1990, 1995 NPTS, and 2001 NHTS

 MSA Size

1990 Adjusted 1995 2001

Without

Vehicle

With

Vehicles

Without

Vehicle

With

Vehicles

Without

Vehicle

With

Vehicles

 ALL 2.28 3.86 3.04 4.38 2.79 4.16

 Not in MSA 1.81 3.80 2.92 4.43 2.61 4.06

 < 250,000 2.87 4.11 2.43 4.54 2.51 4.45

 250,000 to 499,999 1.92 3.95 3.17 4.47 2.56 4.21

 500,000 to 999,999 1.80 3.98 2.69 4.45 2.69 4.28

 1 to 2.9 million 2.23 3.91 3.00 4.41 2.57 4.24

 3 million + 2.50 3.72 3.13 4.26 2.93 4.07

Note:

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. 

Thus, there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The

adjustments to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles

of travel (VMT).

In 2001, people in households without a vehicle averaged 1.3 fewer trips per day than those in

households with vehicles. The impact of owning a vehicle on mobility was the least for those

who lived in large cities. As depicted in Figure 14, almost three-quarters of the trips taken by

those who lived in the largest metropolitan areas and who were without a vehicle were by walk,

bike or public transit. In general, those without access to a privately-owned vehicle met many

of their transportation needs by riding as a passenger in a privately-owned vehicle, or by

walking or bicycling (Figure 14). 
Travel Behavior of Sub-Populations 2001 NHTS Summary of Travel Trends (DRAFT)

56

Figure 14

Mode Distribution of Person Trips Taken by Zero-Vehicle Households

2001 NHTS

Note:

C Other includes other modes not shown above such as RV, motorcycle, other POV, Amtrak, airplane, taxi, bike,

school bus, and other.
2001 NHTS Summary of Travel Trends Glossary

G-1

TRAVEL CONCEPTS AND GLOSSARY OF TERMS
Glossary 2001 NHTS Summary of Travel Trends

G-2

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2001 NHTS Summary of Travel Trends Glossary

G-3

TRAVEL CONCEPTS 

PERSON TRIP DEFINITION -A trip by one person in any mode of transportation. 

This is the most basic and universal measure of personal travel. Each

record in the Travel Day and Travel Period files in the NHTS dataset

represents one person trip.

EXAMPLES - Two household members traveling together in one car

are counted as two person trips. Three household members walking to

the store together are counted as three person trips.

PERSON

MILES OF

TRAVEL (PMT)

DEFINITION - The number of miles traveled by each person on a trip.

EXAMPLES - If two people traveling together take a six-mile subway

trip to the airport, that trip results in 12 person miles of travel. A fourmile van trip with a driver and three passengers counts as 16 person

miles of travel (4 people times 4 miles).
Glossary 2001 NHTS Summary of Travel Trends

G-4

VEHICLE

TRIPS

DEFINITION - A trip by a single privately operated vehicle (POV)

regardless of the number of persons in the vehicle.

EXAMPLES - Two people traveling together in a car would be counted

as one vehicle trip. Four people going to a restaurant in a van is

considered one vehicle trip.

NPTS MODE RESTRICTIONS - To be considered a vehicle trip in

NHTS, the trip must have been made in a POV, namely a householdbased car, van, sport utility vehicle, pickup truck, other truck,

recreational vehicle, motorcycle or other POV. The vehicle does not

need to belong to the household.

Trips made in other highway vehicles, such as buses, streetcars, taxis,

and school buses are collected in the NHTS, but these are shown as

person trips by those modes. The design of the NHTS is such that it

does not serve as a source for vehicle trips in modes such as buses,

because there is no way to trace the movement of the bus fleet

throughout the day. Those interested in vehicle trips by buses, taxis, etc.

need to use a data source that relies on reports from the fleet operators of

those vehicles. The National Transit Database of the Federal Transit

Administration is one such source.

VEHICLE

MILES OF

TRAVEL (VMT)

DEFINITION - One vehicle mile of travel is the movement of one

privately operated vehicle (POV) for one mile, regardless of the number

of people in the vehicle.

EXAMPLES - When one person drives her car 12 miles to work, 12

vehicle miles of travel have been made. If two people travel three miles

by pickup, three vehicle miles of travel have been made.

SAME MODE RESTRICTIONS - For NHTS data, vehicle miles are

restricted to the same privately-operated vehicles as vehicle trips(see

above), that is a household-based car, van, sport utility vehicle, pickup

truck, other truck, recreational vehicle, or other POV.
2001 NHTS Summary of Travel Trends Glossary

G-5

VEHICLE

OCCUPANCY

DEFINITION - For NHTS data, vehicle occupancy is generally

computed as person miles of travel per vehicle mile (referred to as the

travel method). Note that the other commonly-used definition of vehicle

occupancy is persons per vehicle trip (referred to as the trip method) . 

COMMENTS - Because longer trips often have higher occupancies, the

travel method generally yields a higher rate than the trip method. The

calculation of the travel method requires that trip miles be reported, thus

it is calculated on a slightly smaller number of trips than the trip method.
Glossary 2001 NHTS Summary of Travel Trends

G-6

GLOSSARY 

This glossary provides the most common terms used in the NHTS and definitions of

those terms. These definitions are provided to assist the user in the interpretation of the NHTS

data. 

Adult For NHTS, this is defined as a person 18 years or older.

Block Group A subdivision of a Census tract that averages 1000 to 1100 people, and

approximately 400-500 housing units. The source used for the 2001

NHTS was GDT Dynamap 2000 (from Census 2000 TIGER/Line files). 
2001 NHTS Summary of Travel Trends Glossary

G-7

Census Region

and Division

The Census Bureau divides the states into four regions and nine divisions. 

Note that the divisions are wholly contained within a region, i.e., region lines

do not split division lines. The regions and their component divisions are:

Northeast Region:

1. New England Division: Connecticut, Maine, Massachusetts,

New Hampshire, Rhode Island, Vermont

2. Middle Atlantic Division: New Jersey, New York, Pennsylvania

North Central Region:

1. East North Central Division: Illinois, Indiana, Michigan, Ohio,

Wisconsin

2. West North Central Division: Iowa, Kansas, Minnesota,

Missouri, Nebraska, North Dakota, South Dakota

South Region

1. South Atlantic Division: Delaware, Florida, Georgia, Maryland,

North Carolina, South Carolina, Virginia, West Virginia

2. East South Central Division: Alabama, Kentucky, Mississippi,

Tennessee 

3. West South Central Division: Arkansas, Louisiana, Oklahoma,

Texas

West Region

1. Mountain Division: Arizona, Colorado, Idaho, Montana,

Nevada, New Mexico, Utah, Wyoming

2. Pacific Division: Alaska, California, Hawaii, Oregon,

Washington

Puerto Rico

For the 2001 NHTS the source used for the 2000 Census Region was:

http://www.census.gov/geo/www/cob/rg2000.html

The source used for the 2000 Census Division was:

http://www.census.gov/geo/www/cob/dv2000.html

Census Tract A small subdivision of a county, containing approximately 4,000 persons. 

Tracts can range in population from 2,500 to 8,000. The geographic size of the

tract may vary considerably, depending on population density. Tracts were

designed to be homogeneous in regard to population characteristics, economic

status and living conditions when they were first delineated. Since the first

tracts were delineated for the 1890 Census, today’s tracts may be far from

homogeneous. The source used for the 2001 NHTS was GDT Dynamap 2000

(from Census 2000 TIGER/Line files).
Glossary 2001 NHTS Summary of Travel Trends

G-8

Consolidated

Metropolitan

Statistical Area

(CMSA)

A large metropolitan complex of 1 million or more population, containing two

or more identifiable component parts designated as Primary Metropolitan

Statistical Areas (PMSAs). For example, the Boston CMSA is composed of six

PMSAs.

Destination For travel day trips, the destination is the point at which there is a break in

travel, except if the break is only to change vehicles or means of transport. For

travel period trips, the destination is the farthest point of travel.

Driver A driver is a person who operates a motorized vehicle. If more than one person

drives on a single trip, the person who drives the most miles is classified as the

principal driver.

Employed A person is considered employed if (s)he worked for pay, either full time or

part time, during the week before the interview.

Education Level The number of years of regular schooling completed in graded public, private,

or parochial schools, or in colleges, universities, or professional schools,

whether day school or night school. Regular schooling advances a person

toward an elementary or high school diploma, or a college, university, or

professional school degree.

Household A group of persons whose usual place of residence is a specific housing unit;

these persons may or may not be related to each other. The total of all U.S.

households represents the total civilian non-institutionalized population. A

household does not include group quarters (i.e., 10 or more persons living

together, none of whom are related).
2001 NHTS Summary of Travel Trends Glossary

G-9

Household Income Household income is the money earned by all family members in a household,

including those temporarily absent. Annual income consisted of the income

earned 12 months preceding the interview. Household income includes monies

from all sources, such as wages and salary, commissions, tips, cash bonuses,

income from a business or farm, pensions, dividends, interest, unemployment

or workmen’s compensation, social security, veterans’ payments, rent received

from owned property (minus the operating costs), public assistance payments,

regular gifts of money from friends or relatives not living in the household,

alimony, child support, and other kinds of periodic money income other than

earnings. Household income excludes in-kind income such as room and board,

insurance payments, lump-sum inheritances, occasional gifts of money from

persons not living in the same household, withdrawal of savings from banks,

tax refunds, and the proceeds of the sale of one’s house, car, or other personal

property.

Household

Members

Household members include all people, whether present or temporarily absent,

whose usual place of residence is in the sample unit. Household members also

include people staying in the sample unit who have no other usual place of

residence elsewhere.

Household Vehicle A household vehicle is a motorized vehicle that is owned, leased, rented or

company-owned and available to be used regularly by household members. 

Household vehicles include vehicles used solely for business purposes or

business-owned vehicles, so long as they are driven home and can be used for

the home to work trip, (e.g., taxicabs, police cars, etc.). Household vehicles

include all vehicles that were owned or available for use by members of the

household during the travel period, even though a vehicle may have been sold

before the interview. Vehicles excluded from household vehicles are those that

were not working and were not expected to be working, and vehicles that were

purchased or received after the designated travel day.
Glossary 2001 NHTS Summary of Travel Trends

G-10

Means of

Transportation

A mode of travel used for going from one place (origin) to another

(destination). A means of transportation includes private and public modes, as

well as walking. 

The following transportation modes, grouped by major mode, are included in

the NHTS data. 

Private Vehicle

1. Car – A privately owned and/or operated licensed motorized vehicle

including cars and station wagons. Leased and rented cars are included if

they are privately operated and not used for picking up passengers in

return for fare.

2. Van – privately owned and/or operated van or minivan designed to carry

5 to 13 passengers, or to haul cargo.

3. Sport Utility Vehicle – A privately owned and/or operated vehicle that is

a hybrid of design elements from a van, a pickup truck and a station

wagon. Examples include a Chevrolet Blazer, Ford Bronco, Jeep

Cherokee, or Nissan Pathfinder. 

4. Pickup Truck – A pickup truck is a motorized vehicle, privately owned

and/or operated, with an enclosed cab that usually accommodates 2-3

passengers, and an open cargo area in the rear. Later model pickups

often have a back seat that allows for total seating of 4 -6 passengers. 

Pickup trucks usually have the same size of wheel-base as a full-size

station wagon. This category also includes pickups with campers.

5. Other Truck – This category consists of all trucks other than pickup

trucks (i.e., dump trucks, trailer trucks, etc.).

6. RV or Motor Home – An RV or motor home includes a self-powered

recreational vehicle that is operated as a unit without being towed by

another vehicle (e.g., a Winnebago motor home).

7. Motorcycle – This category includes large, medium, and small

motorcycles and mopeds. 

8. Other POV – A vehicle that cannot be classified into one of the

categories above. 
2001 NHTS Summary of Travel Trends Glossary

G-11

Public Transportation

1. Bus – The bus category includes:

a. city to city buses (buses that run from one urban center to the other), 

b. mass transit systems (buses that are available to the general public),

c. school buses, and 

d. charter/tour buses (private bus operating on a fixed schedule

between population centers).

2. Train – This category includes:

a. Amtrak and intercity train (heavy passenger rail that runs form one

urban center to another),

b. Subway and elevated rail (also know as rail rapid transit is a high

capacity system operated on a fixed rail or guide way system on a

private right of way), and

c. Trolley/streetcars (vehicles that run on a fixed rail system powered

by electricity obtained from an overhead power distribution system),

and commuter trains and passenger trains.

Other Modes 

1. Airplane – Airplanes include commercial airplanes and smaller planes

that are available for use by the general public in exchange for a fare. 

Private and corporate planes and helicopters are also included. 

2. Ship – This includes travel by ships, cruise ships, passenger lines and

ferries, sailboats, motorboats and yachts.

3. Taxi – Taxis include the use of a taxicab by a passenger for fare. The

taxi category does not include rental cars if they are privately operated.

4. Limousine – Includes the use of a limousine by passenger for fare. The

limousine category does not include rental cars if they are privately

operated.

5. Hotel/Airport Shuttle – This includes privately operated shuttle buses that

are operated between a limited number of points for a fare.

6. Bicycle – This category includes bicycles of all speeds and sizes that do

not have a motor.

7. Walk. – This category includes walking and jogging. 
Glossary 2001 NHTS Summary of Travel Trends

G-12

8. Other – Includes any types of transportation not previously listed, e.g.

skate boards. 

Metropolitan

Statistical Area

(MSA)

Except in the New England States, a Metropolitan Statistical Area is a county

or group of contiguous counties which contains at least one city of 50,000

inhabitants or more, or “twin cities” with a combined population of at least

50,000. In addition, contiguous counties are included in an MSA if, according

to certain criteria, they are socially and economically integrated with the central

city. In the New England States, MSA’s consist of towns and cities instead of

counties. The source used for the 2001 NHTS was 1999 Metropolitan Areas:

Cartographic Boundary Files. File ma99_99.shp from

http://www.census.gov/geo/www/cob/ma1999.html.

Motorized

Vehicle

Motorized vehicles are all vehicles that are licensed for highway driving. 

Occupancy Occupancy is the number of persons, including driver and passenger(s)

in a vehicle. NHTS occupancy rates are generally calculated as person

miles divided by vehicle miles.

Origin Origin is the starting point of a trip. 

Overlap Trip A travel period trip that occurs on travel day, and is thus collected in

both portions of the NHTS questionnaire. To ensure that this trip is not

counted twice, eliminate overlap trips from travel day data when travel

day and travel period data will be added together. 

Passenger For a specific trip, a passenger is any occupant of a motorized vehicle,

other than the driver.

Person Miles of

Travel (PMT)

PMT is a primary measure of person travel. When one person travels

one mile, one person mile of travel results. Where 2 or more persons

travel together in the same vehicle, each person makes the same number

of person miles as the vehicle miles. Therefore, four persons traveling 5

miles in the same vehicle results in 20 person miles (4 x 5 = 20). 
2001 NHTS Summary of Travel Trends Glossary

G-13

Person Trip A person trip is a trip by one or more persons in any mode of

transportation. Each person is considered as making one person trip. 

For example, four persons traveling together in one auto are counted as

four person trips.

POV A privately-owned vehicle or privately-operated vehicle. Either way, the

intent here is that this is not a vehicle available to the public for a fee,

such as a bus, subway, taxi, etc. 

Travel Day A travel day is a 24-hour period from 4:00 a.m. to 3:59 a.m. designated

as the reference period for studying trips and travel by members of a

sampled household.

Travel Period A travel period consists of a four-week period ending with the travel

day. 

Travel Day Trip A travel day trip is defined as any time the respondent went from one

address to another by private motor vehicle, public transportation,

bicycle, walking, or other means. However, a separate trip is not

counted in two instances:

1. When the sole purpose for the trip is to get to another vehicle or

mode of transportation in order to continue to the destination. 

2. Travel within a shopping center, mall or shopping areas of 4-5

blocks is to be considered as travel to one destination. 

Travel Period

Trip

A travel period trip is a trip where the farthest destination is at least 50

miles from home. The outgoing portion of this trip can take place at any

time, but the return must be within the four-week travel period. The

four-week travel period ends on and includes the assigned travel day.

Travel Day Trip

Purpose

A trip purpose is the main reason that motivates a trip. There are 36

travel day trip purposes used in the 2001 NHTS. 
Glossary 2001 NHTS Summary of Travel Trends

G-14

For the 2001 Survey, trip purposes were collected using a From-To

approach. For each trip, the origin and destination are on the file in

generic terms, e.g. from work to shopping. The 36 trip reasons are

defined as follows, and shown with their coded trip purpose number.

1. To Home – Travel to home after leaving for some reason. 

11. Go to Work – The first trip to the work location on travel day.

12. Return to Work – A trip to work that is not the first trip to work on

the travel day.

13. Attend Business Meeting/Trip – A work related trip whose purpose

is to attend a business meeting.

14 Other Work Related – A work related trip whose purpose is not

specifically to attend a business meeting.

20. Other School/Religious Activity – School and religious activities

not covered by categories 21 through 23 below.

21. Go to School as a Student – A trip whose purpose is to go to school

as a student.

22. Go to Religious Activity – A trip whose purpose is to go to a place

to attend a religious activity.

23. Go to Library, School Related – A trip whose purpose is to go to

the library as part of a school related activity.

24. Go to Daycare – A trip whose purpose is to attend day care.

30. Medical/Dental Services – A trip made for medical, dental, or

mental health treatment, or other related professional services.

40. Shopping/Errands – Shopping/errand trips not covered by

categories 41 through 43 below.

41. Buy Goods, (e.g., groceries/clothing/hardware store) – A shopping

trip whose purpose is to purchase commodities for use or

consumption elsewhere. This purpose also includes windowshopping and trip made to shop even if nothing is purchased. 
2001 NHTS Summary of Travel Trends Glossary

G-15

42. Buy Services, (e.g., video rentals/dry cleaning/post office/car

service/bank) – The category includes the purchase of services

other than medical/dental or other professional services.

43. Buy Gas – A trip made specifically to get gas.

50. Social/Recreational – Includes social and recreational trips not

covered by categories 51 through 55 below.

51. Go to the Gym/Exercise/Play Sports – A trip made for exercise or

to participate in a sport. 

52. Rest or Relaxation/Vacation. 

53. Visit Friends/Relatives – The social/recreational trip whose

purpose is to visit with family and friends.

54. Go out/Hang out, Entertainment/Theater/Sports Event/Go to Bar – 

The purpose of the trip is entertainment or hanging out with

friends.

55. Visit Public Place, Historical Site/Museum/Park/Library. 

60. Family Personal Business/Obligations – A trip for personal

business not covered by categories 61 through 65 below.

61. Use Professional Services, Attorney/Accountant – A trip made for

professional services other than for medical/dental purposes.

62. Attend Funeral/Wedding – A personal trip to attend a funeral or a

wedding.

63. Use Personal Services, Grooming/Haircut/Nails – A trip for

personal services such as to a hairdresser.

64. Pet Care, Walk the dog/Vet visits. 

65. Attend Meeting, PTA/Home Owners Association/Local

Government – The purpose of the trip is to attend a non-work

related meeting, such as a community meeting.

70. Transport Someone – Trips with a passenger that are related to

picking up or dropping off someone but not covered by categories

71 through 73 below.

71. Pickup Someone. 
Glossary 2001 NHTS Summary of Travel Trends

G-16

72. Take and Wait – A trip made to take someone to a destination and

then wait with them at the destination and return together.

73. Drop Someone Off. 

80. Meals – A trip whose purpose is to eat or get a meal but not

covered by categories 81 through 83 below.

81. Social Event – A trip whose purpose is to eat a meal at a social

event.

82. Get/Eat Meal – A trip whose purpose is to get and eat a meal but

not at a social event.

83. Coffee/Ice Cream/Snacks – A trip whose purpose is to get/eat a

snack or drink, something less than a meal.

91. Other – A trip purpose not covered by categories above.

Travel Period

Trip Purpose

A trip purpose is the main reason that motivates a trip. There were 18

travel period trip purposes in the 2001 NHTS. The main reason and all

other reasons for the trip were collected.

Urbanized Area An urbanized area consists of the built up area surrounding a central core

(or central city), with a population density of at least 1,000 persons per

square mile. Urbanized areas do not follow jurisdictional boundaries

thus it is common for the urbanized area boundary to divide a county.

For the 2001 NHTS, Urban Areas were calculated two ways.

1. Variable URBAN uses the 2000 Urbanized Areas: Cartographic

Boundary Files. File ua00_d00.shp from

http://www.census.gov/geo/www/cob/ua2000.html. Two codes are

used: 0 = Not in Urban Area, 1 = in Urban Area.

2. Variable URBAN1 uses the 2000 Urbanized Areas: Cartographic

Boundary Files. File ua00_d00.shp from

http://www.census.gov/geo/www/cob/ua2000.html. Three codes

are used: 0 = Not in Urban Area, 1 = in Urban Cluster, 2 = in

Urban Area, 3 = in area surrounded by urban areas.
2001 NHTS Summary of Travel Trends Glossary

G-17

Vehicle The 2001 NHTS, the term vehicle includes autos, passenger vans, sport

utility vehicles, pickups and other light trucks, RV’s, motorcycles and

mopeds owned or available to the household.

Vehicle Miles of

Travel (VMT)

VMT is a unit to measure vehicle travel made by a private vehicle, such

as an automobile, van, pickup truck, or motorcycle. Each mile traveled

is counted as one vehicle mile regardless of the number of persons in the

vehicle. 

Vehicle

Occupancy

Vehicle occupancy is the number of persons, including driver and 

passenger(s) in a vehicle; also includes persons who did not complete a

whole trip. NHTS occupancy rates are generally calculated as person

miles divided by vehicle miles. 

Vehicle Trip A trip by a single privately-operated vehicle (POV) regardless of the

number of persons in the vehicle. 
Glossary 2001 NHTS Summary of Travel Trends

G-18

Vehicle Type For purposes of the 2001 NHTS, one of the following: 

1. Automobile (including station wagon)

2. Van 

3. Sport Utility Vehicle 

4. Pickup Truck (including pickup with camper)

5. Other Truck

6. RV or Motor Home

7. Motorcycle

8. Other 
2001 NHTS Summary of Travel Trends Appendix 1

A1-1

APPENDIX 1

SELECTED TABLES INCLUDING TRAVEL OF

INDIVIDUALS 0 to 4 YEAR-OLDS
Appendix 1 2001 NHTS Summary of Travel Trends

A1-2

This page intentionally left blank.
2001 NHTS Summary of Travel Trends Appendix 1

A1-3

Table 5

Average Annual PMT, Person Trips and Trip Length by Trip Purpose

1983, 1990, 1995 NPTS, and 2001 NHTS

(2001 NHTS contains 0 to 4 year-olds)

 Trip Purpose 1983 1990 1990 

Adjusted 1995 2001 

Average Annual PMT per Household

All Purposes 22,802 24,803 30,316 34,459 37,002

To/From Work 4,586 5,637 5,637 7,740 6,706

Work Related Business 1,354 1,043 1,043 1,987 2,987

Shopping 2,567 2,674 3,343 4,659 5,188

All Other Fam/Per Business 3,311 5,083 7,167 7,381 7,245

School/Church 1,522 1,599 1,599 1,973 2,198

Social and Recreational 8,964 8,567 11,308 10,571 11,281

Other 500 195 214 131 1,262

Average Annual Person Trips per Household

All Purposes 2,628 2,673 3,262 3,828 3,793

To/From Work 537 539 539 676 565

Work Related Business 62 38 38 100 109

Shopping 474 504 630 775 749

All Other Fam/Per Business 456 606 854 981 938

School/Church 310 304 304 337 373

Social and Recreational 728 662 874 953 1,022

Other 61 20 22 6 32

Average Person Trip Length (miles)

All Purposes 8.68 9.45 9.47 9.13 9.94

To/From Work 8.54 10.65 10.65 11.63 12.11

Work Related Business 21.77 28.20 28.20 20.28 28.26

Shopping 5.41 5.38 5.38 6.08 7.03

All Other Fam/Per Business 7.27 8.55 8.55 7.63 7.85

School/Church 4.90 5.39 5.39 5.98 6.02

Social and Recreational 12.31 13.19 13.19 11.27 11.27

Other 8.22 10.30 10.30 22.83 41.52

Note: 

• Average person trip length for 199, 1995, and 2001 is calculated using only those records with trip mileage information present.

• All tables reporting totals could include some unreported characteristics.

• Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus, there are

limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments to 1990 data affect

only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).
Appendix 1 2001 NHTS Summary of Travel Trends

A1-4

Table 7

Average Annual Person Trips per Household

by Mode of Transportation and MSA Size

1977, 1983, 1990, 1995 NPTS, and 2001 NHTS

(2001 NHTS contains 0 to 4 year-olds)

Mode of Transportation

SMSA or MSA Size 1977 1983 1990 1990 Adjusted 1995 2001

Private

ALL 2,351 2,152 2,329 2,861 3,307 3,276

Not in (S)MSA 2,436 2,322 2,306 2,837 3,492 3,251

Less than 250,000 2,517 2,375 2,508 3,090 3,503 3,481

250,000 - 499,999 2,574 2,443 2,461 3,014 3,472 3,425

500,000 - 999,999 2,628 2,140 2,413 2,957 3,509 3,519

1,000,000 - 2,999,999 2,366 2,031 2,430 2,986 3,354 3,362

3,000,000 and above 1,785 1,691 2,160 2,649 3,075 3,108

PublicTransit

ALL 73 60 52 58 67 60

Not in (S)MSA 22 11 13 14 9 6

Less than 250,000 47 17 27 30 23 12

250,000 - 499,999 44 23 19 22 18 22

500,000 - 999,999 58 48 28 33 33 12

1,000,000 - 2,999,999 86 67 46 52 37 38

3,000,000 and above 189 181 112 124 137 134

Walk

ALL 261 226 193 234 205 329

Not in (S)MSA 199 211 146 175 134 232

Less than 250,000 241 280 172 212 138 262

250,000 - 499,999 206 199 165 203 152 267

500,000 - 999,999 256 184 132 161 138 238

1,000,000 - 2,999,999 295 179 170 207 162 292

3,000,000 and above 396 330 278 337 301 455

ALL MODES

ALL 2,808 2,628 2,673 3,262 3,828 3,793

Not in (S)MSA 2,800 2,766 2,580 3,151 3,878 3,624

Less than 250,000 2,944 2,889 2,816 3,450 3,926 3,872

250,000 - 499,999 2,945 2,891 2,741 3,340 3,894 3,842

500,000 - 999,999 3,049 2,542 2,667 3,252 3,916 3,881

1,000,000 - 2,999,999 2,861 2,463 2,737 3,344 3,795 3,814

3,000,000 and above 2,459 2,326 2,641 3,213 3,765 3,830

Note:

C The population size groups for 1977 - 1983 NPTS are SMSA Size Groups and 1990 - 2001 are MSA Size Groups.

C In 2001, the mode “Bus” was divided into “Local Public Transit Bus,” “Commuter Bus,” “Charter/tour bus,” and “City to city bus.” Only “Local

Public Transit Bus” and “Commuter Bus” are included in public transit calculations.

C All modes includes other modes not specified such as bike, school bus, taxi and other.

C All tables reporting totals could include some unreported characteristics.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus, there are limits on the

conclusions that can be drawn in comparing travel with earlier survey years. The adjustments to 1990 data affect only person trips, vehicle trips,

person miles of travel (PMT) and vehicle miles of travel (VMT).
2001 NHTS Summary of Travel Trends Appendix 1

A1-5

Table 8

Person Trips per Household by Household Income

1983, 1990, and 1995 NPTS and 2001 NHTS

Income 1983 1990 1990 

Adjusted 1995 2001

Annual

Compounded

Rate,

1990-2001

ALL 2,628 2,673 3,262 3,828 3,793 1.4%

< $10,000 1,407 1,710 2,098 2,137 2,196 0.4%

$10 to $20,000 1,927 1,968 2,412 2,790 2,689 1.0%

$20 to $30,000 2,376 2,455 3,008 3,522 3,248 0.7%

$30 to $40,000 2,739 2,802 3,431 3,980 3,730 0.8%

$40 to $50,000 3,037 3,101 3,791 4,298 4,134 0.8%

$50 to $60,000 3,284 3,391 4,138 4,539 4,618 1.0%

$60 to $70,000 3,485 3,660 4,458 4,726 4,828 0.7%

$70 to $80,000 3,635 3,832 4,659 4,855 5,161 0.9%

$80,000+ 3,602 3,747 4,570 4,829 5,251 1.3%

Unreported 2,090 2,536 3,424 2,499 -0.1%

Note:

• Incomes for 1983, 1990, adjusted 1990, and 1995 have been adjusted to 2001 dollars.

• All tables reporting totals could include some unreported characteristics.

• Note that only the 1990 person trip data have been adjusted to make them more comparable

with the 1995 and 2001 data. Thus, there are limits on the conclusions that can be drawn in

comparing travel with earlier survey years. The adjustments to 1990 data affect only person

trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).
Appendix 1 2001 NHTS Summary of Travel Trends

A1-6

Table 9

Total Person Trips by Mode of Transportation and Trip Purpose

Adjusted 1990 and 1995 NPTS, and 2001 NHTS

(millions)

(2001 NHTS contains 0 to 4 year-olds)

Total

To or

From

Work

Work

Related

Business

Family and

Personal

Business

School

or

Church

Social and

Recreational Other

Private

1990 Adj 267,029

(87.7%)

45,856

(91.1%)

3,178

(90.1%)

128,368

(92.6%)

17,545

(61.8%)

70,382

(86.3%)

1,629

(80.9%)

1995 327,400

(86.4%)

60,740

(90.8%)

8,835

(89.6%)

156,065

(89.8%)

22,436

(67.3%)

78,809

(83.5%)

470

(75.4%)

2001 351,692

(86.4%)

56,054

(92.4%)

10,648

(91.2%)

164,766

(91.0%)

28,970

(72.4%)

88,475

(80.6%)

2,350

(68.4%)

Public Transit

1990 Adj 5,460

(1.8%)

1,992

(4.0%)

92

(2.6%)

1,318

(1.0%)

1,076

(3.8%)

946

(1.2%)

35

(1.7%)

1995 6,638

(1.8%)

2,328

(3.5%)

123

(1.2%)

2,000

(1.2%)

826

(2.5%)

1,350

(1.4%)

11

(1.8%)

2001 6,475

(1.6%)

2,271

(3.7%)

213

(1.8%)

1,954

(1.1%)

825

(2.1%)

1,057

(1.0%)

134

(3.9%)

Walk

1990 Adj 21,879

(7.2%)

1,999

(4.0%)

154

(4.4%)

7,722

(5.6%)

3,649

(12.8%)

8,090

(9.9%)

265

(13.2%)

1995 20,325

(5.4%)

1,510

(2.3%)

240

(2.4%)

8,756

(5.0%)

2,925

(8.8%)

6,845

(7.3%)

47

(7.6%)

2001 35,366

(8.7%)

1,715

(2.8%)

487

(4.2%)

12,744

(7.0%)

3,737

(9.3%)

16,108

(14.7%)

527

(15.3%)

Other

1990 Adj 9,867

(3.2%)

428

(0.8%)

95

(2.7%)

1,087

(0.8%)

6,086

(21.4%)

2,098

(2.6%)

73

(3.6%)

1995 12,099

(3.2%)

887

(1.3%)

417

(4.2%)

1,768

(1.0%)

6,035

(18.1%)

2,954

(3.1%)

37

(6.0%)

2001 13,345

(3.3%)

584

(1.0%)

317

(2.7%)

1,540

(0.9%)

6,463

(16.1%)

4,000

(3.6%)

408

(11.9%)

TOTAL

1990 Adj 304,471

(100%)

50,314

(100%)

3,529

(100%)

138,559

(100%)

28,397

(100%)

81,575

(100%)

2,014

(100%)

1995 378,930

(100%)

66,901

(100%)

9,860

(100%)

173,764

(100%)

33,355

(100%)

94,362

(100%)

623

(100%)

2001 407,262

(100%)

60,690

(100%)

11,676

(100%)

181,119

(100%)

40,026

(100%)

109,732

(100%)

3,434

(100%)

Note:

C All tables reporting totals could include some unreported characteristics.
2001 NHTS Summary of Travel Trends Appendix 1

A1-7

C In 2001, the mode “Bus” was divided into “Local Public Transit Bus,” “Commuter Bus,” “Charter/tour bus,” and

“City to city bus.” Only “Local Public Transit Bus” and “Commuter Bus” are included in public transit calculations.

C Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus,

there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments

to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).
Appendix 1 2001 NHTS Summary of Travel Trends

A1-8

Table 28

Distribution of Person Trips by Start Time of Trip

1983, 1990, 1995 NPTS, and 2001 NHTS

(2001 NHTS contains 0 to 4 year-olds)

Time of Day 1983 1990 1990

 Adj 1995 2001

 10 pm - 1 am 4.0 4.0 4.1 3.5 2.8

 1 - 6 am 3.3 1.9 1.8 1.7 1.8

 6 - 9 am 14.4 13.9 12.5 13.8 14.2

 9 am - 1 pm 23.4 20.1 20.6 24.2 24.8

 1 - 4 pm 20.8 20.4 20.7 22.1 22.2

 4 - 7 pm 21.2 22.8 22.9 23.0 22.4

 7 - 10 pm 12.3 12.8 13.2 11.8 11.7

 ALL 100.0 100.0 100.0 100.0 100.0

• Note:

• All tables reporting totals could include some unreported characteristics.

• Note that only the 1990 data have been adjusted to make them more comparable with the 1995 and 2001 data. Thus,

there are limits on the conclusions that can be drawn in comparing travel with earlier survey years. The adjustments

to 1990 data affect only person trips, vehicle trips, person miles of travel (PMT) and vehicle miles of travel (VMT).
2001 NHTS Summary of Travel Trends Appendix 2

A2-1 

APPENDIX 2

KEY CHANGES IN THE 2001 NHTS SURVEY

METHODOLOGY AND CONTENT
Appendix 2 2001 NHTS Summary of Travel Trends

A2-2 

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2001 NHTS Summary of Travel Trends Appendix 2

A2-3 

APPENDIX 2

KEY CHANGES IN THE 2001 NHTS SURVEY METHODOLOGY AND CONTENT

(Source: Exhibit 3-1, 2001 NHTS User’s Guide)

TOPIC FROM TO PROBABLE IMPACTS

What is

collected?

Two separate

surveys - the NPTS

and the ATS

Combined survey

that collects both

travel day and travel

period information

Enables analysis of

relationship between daily

and long-distance travel

characteristics of each person

Which

household

members are

eligible?

Household members

age 5

and older

All household

members

More complete trip reporting

When proxy

needed?

Proxy for household

members 5 to 13

years

Proxy for household

members under 16

years

• Increase in number of

interviews by proxy

• Obtain parental approval

when speaking with 14 and

15 year olds

Respondent

Contact

Advance letter Advance letter with a

$5 cash incentive and

a brochure

• Improved response

• Legitimizes the survey

with respondents

Use of a

diary for

long trips

The ATS used a

diary to record longdistance trips

No travel period

diary included

Lower respondent burden and

reduce the possibility of

confusion due to the mailing

of both a travel day and

travel period diary
Appendix 2 2001 NHTS Summary of Travel Trends

TOPIC FROM TO PROBABLE IMPACTS

A2-4 

Travel day

trip

definition

Any stop from one

address to the next is

a separate trip

Basically the same -

stops only to change

a mode of

transportation

excluded

• May improve reporting of

trips by public

transportation as subjects

were specifically reminded

about these trips

• No change mode trips

were recorded except

where public

transportation was

involved

Walk and

bike trips on

travel day

No specific mention

of walk and bike

trips

Specific reminder to

include walk, bike

rides and trips that

started and ended in

the same place

Will increase the reporting of

walk and bike trips

Travel day

trip purpose

There were 17 trip

purpose categories

There are 36 trip

purpose categories

The new categories more

accurately capture responses

Most recent

long distance

trip

Not collected Collected Facilitate the imputation of

trips for persons with no

reported long distance trips in

travel period

Odometer

readings

Readings collected

by contacting the

respondent by phone

or by mail

Data collection

modes also included

the Internet, fax, and

a toll-free 800

number

Improved response

Geo-coding Limited use of

manual geo-coding

Extensive use of

manual geo-coding

Higher geo-coding success

rates and more accurate geocoding
2001 NHTS Summary of Travel Trends Appendix 2

TOPIC FROM TO PROBABLE IMPACTS

A2-5 

Travel

period

length and

travel period

trip

definition

The NPTS included

trips of 75 miles or

more and used a 2-

week recall period. 

The ATS included

trips of 100 miles or

more taken over a

full year (4

interviews). 

The travel period was

a four-week period.

Trips of 50 miles or

more from home

were defined as long

distance.

Four-week travel period and

shorter criterion distance

provides information on a

larger sample of longdistance trips than NPTS and

better recall of trips than

ATS (if not recorded in ATS

diary), but a smaller sample

of trips and greater difficulty

estimating annual longdistance trip rates than ATS. 

The 4-week travel period

may have increased the

potential for telescoping (i.e.,

bringing trips into the travel

period).

Splitting

walk and

bike trips at

the end of

travel day

Not conducted Conducted Walk and bike trip rates may

be higher than on past NPTSs

Adding trips

not reported

by household

members

interviewed

earlier

Not conducted Conducted More complete trip reporting
Appendix 2 2001 NHTS Summary of Travel Trends

TOPIC FROM TO PROBABLE IMPACTS

1 In raking, one adjusts estimates to agree to one set of controls (e. g., ethnicity), then adjusts

estimates to a second set of controls (e. g., region), etc. This process is then repeated until all

estimates are simultaneously close to the full set of controls.

A2-6 

Weighting Raking to control

totals1

Several stages of

separate nonresponse

adjustment and

trimming as well as

raking. 

Changes to cells used

for raking.

Presently unknown. 

An evaluation is to be

conducted.
2001 NHTS Summary of Travel Trends Appendix 3

A3-1 

APPENDIX 3

ADJUSTMENT OF 1990 TRAVEL DATA
Appendix 3 2001 NHTS Summary of Travel Trends

A3-2 

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2001 NHTS Summary of Travel Trends Appendix 3

A3-3 

APPENDIX 3

ADJUSTMENT OF 1990 TRAVEL DATA

The 1995 Nationwide Personal Transportation Survey (NPTS) was a significant

improvement over previous surveys in the NPTS series. Different methods were used to ensure that

more complete trip reporting was obtained. Specifically,

S a travel diary was used by respondents in the 1995 survey, in lieu of memory recalling;

and

S “household rostering” was used to capture some trips that may otherwise have been

overlooked.

Although these improvements enhance the completeness and accuracy of trip reporting, they

prevent any direct comparisons between the 1990 and 1995 travel data. Any travel changes

observed between the 1990 and 1995 surveys now reflect not only actual changes in travel during

the period but also artifacts of differences in survey methodology. That is, any changes observed

between the 1990 and 1995 travel data are presumably attributable to: (1) actual changes in travel

behavior, (2) use of travel diaries, (3) use of household rostering, and (4) other improvements in

the 1995 survey method such as a better coding scheme to decipher trip purposes. The latter is

expected to have a smaller effect than the first three factors. Since no data are available to quantify

the impact of these “other” improvements, their impacts are not evaluated in this exercise.

However, the improved coding scheme in 1995 had an effect on trip recording. In 1990,

1.9 billion trips were coded as “other” trip purpose. In 1995, this number was 700 million, a

decline of 64%. These “other” trips are those that can not be classified into any of the existing trip

purpose categories. Two reasons contribute to this substantial decrease in “other” trips. First, the

information was collected in the 1995 survey on “from” where the trip was originated and “to”
Appendix 3 2001 NHTS Summary of Travel Trends

A3-4 

where the trip was destined. This type of “to” and “from” information enabled the trip purposes

to be determined more accurately. As a result, the number of trips with unspecified trip purposes

decreased. Second, better schemes to code trip purposes were used both during and after the data

collection phase, significantly reducing the ambiguity in trip purposes. 

The reduction in trips with unspecified trip purposes presumably increases the number of

trips categorized into the proper trip purpose categories. Ideally, one should remove all artifacts

that result from an improved method. However, data to address the effects of each of the individual

improvements are extremely limited. Our approach was developed to remove as many artifacts that

the data allow. Specifically, our approach quantified and removed the effect of the travel diary and

household trip rostering on the amount and type of trips in the 1995 NPTS.

Adjustment Approach

To more accurately reflect travel trends, the 1990 travel data were adjusted to account for

two major changes in survey methodology: (1) travel diary, and (2) household rostering. In

essence, the 1990 travel data were adjusted in such a way as if a travel diary and household

rostering were used in the 1990 survey. The theory is that more trips would have been recorded

in the 1990 survey if travel diaries were used. This theory is supported by data collected in the

1995 NPTS pre-test. Data from the 1995 NPTS pre-test showed that travel diaries led to more

complete reporting, particularly for incidental trips, such as stopping at a convenience store, which

are often forgotten and, therefore, difficult to capture in a household travel survey. Household

rostering is also expected to capture more complete trip reporting by helping remind respondents

of forgotten trips. Since data from the 1995 NPTS pre-test suggest that the impact of travel diary

varies for different trip purposes, separate adjustment factors were developed for different purposes.

Although more detailed trip purpose information was collected in the 1995 survey, for this

analysis trip purposes were grouped into four broad categories: (1) work and school, (2) shopping,
2001 NHTS Summary of Travel Trends Appendix 3

A3-5 

(3) family and personal business other than shopping, and (4) social and recreational. Separating

shopping trips from trips taken for other family and personal businesses is based on the belief that

travel diaries and household rostering influence reporting on these trips differently. This appendix

describes the approach used to quantify impacts of travel diary and household rostering on the

number of person trips recorded by these purposes.

Rather than adjust travel data in all previous surveys (e.g., 1969, 1983 NPTS), only 1990

travel data were adjusted. Both original and adjusted 1990 statistics are presented in this report.

The user is warned not to compare 1995 results to those from previous NPTS. For trend analysis,

the 1995 results should only be compared to the adjusted 1990 statistics.

Impact of Travel Diary on Trip Reporting

A methodological experiment was designed as part of the 1995 NPTS pre-test to test three

different survey methods: memory recall (n=875), memory jogger (n=729), and travel diary

(n=708). Although the pre-test sample sizes are not particularly large, these pretest data provide

the only platform to quantify the impact of travel diaries on trip reporting. On an individual basis,

using a travel diary indeed captures more trips than recalling the day’s trips from the memory

(Table A3.1). It was found that the diary method averaged 0.5 trips more per person per day than

the recall, or retrospective method [1]. In addition, travel diary use has greater impact on reporting

non-work or non-school related trips than on work or school trips. Its impact is the greatest for

non-shopping types of family and personal travel, such as visiting a doctor’s office, dropping off

or picking up someone: 37% more such trips were reported by using travel diaries than by recalling

from memory.
Appendix 3 2001 NHTS Summary of Travel Trends

A3-6 

Table A3.1. Annual Person Trips per Person by Survey Methods

Based on 1995 NPTS Pre-test Data

Travel Diary 

(1)

Recall

(2)

% Different = [(1)-(2)]/(2)

Work and school 312.50 341.64 -8.5%

Shopping 273.09 226.20 20.7%

Other family and personal 317.47 231.36 37.2%

Social and recreational 293.82 244.39 20.2%

Other 8.29 7.58 9.4%

ALL 1,205.17 1,051.17 14.7%

The ratio of travel rates between those collected by travel diaries and those by recall

approximates the additional trips that would have been reported if travel diaries were used in the

1990 survey. Contrary to our assumption that travel diaries will not increase the number of work

and school trips reported, there were fewer work and school trips reported in the 1995 NPTS pretest when travel diaries were used rather than recall. For trip purposes other than work and school,

travel diaries capture more trips than recall (Table A3.1). Since travel diaries are not believed to

improve the reporting of non-incidental trips such as commute or school trips and since there is no

other evidence supporting a decrease in commute or school trips from 1990 to 1995, the impact of

travel diaries on reporting these trips is considered null, and no adjustment was made to the 1990

data. 

Impact of Household Rostering on Trip Reports

In "household rostering," the interviewer has the benefit of trip data from all household

members who had already been interviewed. For example, suppose person #1 took a trip and

reported that persons #2 and #3 were on the trip with him. When persons #2 and #3 were

interviewed, they were asked to confirm that they were on the trip with person #1. If they were,
2001 NHTS Summary of Travel Trends Appendix 3

A3-7 

the trip characteristics were “copied” from person #1’s record to those of person #2 and person #3.

If person #2 or person #3 indicated that they were not on the trip with person #1, this response was

accepted. One benefit of household rostering is that it aids the memory of the respondent and

improves trip reporting. 

If household rostering had been used in the 1990 NPTS, how many more trips would have

been reported? Unfortunately, this question can not be answered directly due to the lack of data.

Instead, an indirect approach was developed. The basic idea behind this approach is simple: It is

assumed that household rostering does not increase trip reporting from 1990 to 1995 for trips where

only one household member is on the trip. Therefore, the travel trends observed between 1990 and

1995 in the “non-accompany” trips are basically due to (1) changes in travel behavior, (2) use of

travel diaries, and (3) other improvements in the 1995 survey method (these effects being relatively

inconsequential). It should be emphasized that the “non-accompany” trips are not necessarily all

single-occupant trips. Rather, they are trips where only one household member is on the trip, with

or without being accompanied by non-household members. These trips are referred hereafter as

“non-accompany trips.”

After adjusting these “non-accompany” trips in 1990 for the impact of travel diaries, the

remaining difference between the 1990 and 1995 “non-accompany” trip rates is presumably

attributable to the change in travel during the period. Now, adjusting all of the 1990 trips to reflect

the impact of trip diary and the change in travel during the five year period, the remaining

difference between the 1995 survey data and the adjusted 1990 data presumably reflects the impact

of household rostering.

Table A3.2 illustrates the steps taken to estimate the real changes in trip rates observed in

the “non-accompany” trips from 1990 to 1995. The total numbers of “non-accompany” trips

reported in the 1990 NPTS are in Column 1. The impact of using travel diaries on reporting trips
Appendix 3 2001 NHTS Summary of Travel Trends

A3-8 

are listed in Column 2. Adjusting 1990 data for diary impact, Column 3 reports the estimated

number of trips by purpose that would have been collected in 1990 had travel diaries been used.

Comparing the adjusted 1990 figures (Column 3) to comparable 1995 data (Column 4), one can

calculate the percentage change in travel from 1990 to 1995 by trip purpose. The overall increase

is nearly 30%, approximately 4.5% per year for the five year period. 

Table A3.2. Estimated Travel Changes from 1990 to 1995

Based on trips without other household members “accompanied”

Purpose

(1) (2) (3)=(1)x[(=1+(2)] (4) (5)=

[(4)-(3)]/(3)

1990 1-hhm1

 trips

(000)

Diary

Impact2

(%)

1990 1-hhm trips

adjusted for

diary impact

1995 1-hhm trips

(000)

change

in travel

(%)

Work, School 62,973,929 0 62,973,929 84,974,961 34.9

Shopping 27,983,544 20.7 33,860,088 45,996,625 35.8

Other Fam/Per 33,237,593 37.2 45,535,502 58,602,172 28.7

Soc/Rec 33,166,604 20.2 39,799,925 46,509,286 16.9

Other 1,233,007 9.4 1,343,978 356,444 -73.5

TOTAL 158,594,677 182,383,879 236,439,488

1

 1-household-member (1-hhm) trips = Trips where no other household members “accompanied.”

2

 From Table 1.

This approach suggests that Americans as a whole took approximately 35 percent more

commute and school trips from 1990 to 1995. A number of factors could contribute to this increase

in the total number of work and school trips. For example, the number of workers increased by

11% during this period. Note that the number of “other” trips decreased by 74% due to a better

trip purpose coding scheme. The lack of appropriate and sufficient data prohibits an evaluation of

the impact of this improved coding scheme. Thus, no adjustments are made to 1990 trips

categorized as “other” trip purpose. These trips are a very small proportion of all trips.
2001 NHTS Summary of Travel Trends Appendix 3

A3-9 

With these calculations, the revised estimates of 1990 trips now reflect adjustments for (1)

trip diary and (2) change in travel. Presumably, the remaining difference between the 1995 survey

data and the adjusted 1990 data reflects the impact of household rostering. Table A3.3

demonstrates the steps to estimate this effect. First, the number of trips collected in the 1990 survey

was adjusted for the diary impact (e.g., 21% for shopping trips) and for the change in travel

between 1990 and 1995 (e.g., 36% for shopping trips). It can be reasonably assumed that after this

adjustment the 1990 data are almost comparable to the 1995 data except for the impact of

household rostering. The percentage difference between this adjusted 1990 data and the observed

1995 data is used to estimate the impact of household rostering (Table A3.3). Based on this

somewhat convoluted approach, we estimated that approximately 4% more shopping trips would

have been reported in the 1990 survey if household rostering had been used. Again, the number

of “other” trips decreased by 74% due to a better trip purpose coding scheme. The lack of

appropriate and sufficient data prohibits an evaluation of the impact of this improved coding

scheme. Thus, no adjustment is done to 1990 trips categorized with the “other” trip purpose.

Table A3.3. Estimated Impacts of Household Rostering by Trip Purpose

Purpose

(1) (2) (3) (4)=

(1) x [(2)+(3)]/100

(5) (6)=

[(5)-(4)]/(4)

1990

Total Trips

(000)

Diary

Impact

(%)

change

in travel

(%)

1990 trips adjusted

for diary impact

and % change in

travel

1995

Total Trips

(000)

impact of

trip rostering

(%)

Work, School 82,240,011 0 34.9 110,941,885 110,115,282 -0.7

Shopping 47,056,740 20.7 35.8 73,643,798 76,688,225 4.1

Other Fam/Per 56,551,552 37.2 28.7 93,819,025 97,075,588 3.5

Soc/Rec 61,799,215 20.2 16.9 84,726,724 94,361,999 11.4

Other 1,914,779 9.4 -73.5 687,406 689,270 0.3

Adjustment Factors for 1990 Travel Data

By combining the impact of travel diary (Column 2 of Table A3.3) and the impact of
Appendix 3 2001 NHTS Summary of Travel Trends

A3-10 

household rostering (Column 6 of Table A3.3), the factors used to adjust 1990 travel data range

from no adjustment for work and school trips to a 41% increase for trips taken for other family and

personal business (i.e., non-shopping trips) (Table A3.4). These adjustment factors suggest that

between 1990 and 1995 the total number of person trips increased about 4.5% per year, compared

to a rate of 2.6% between 1969 and 1990. However, after taken into account the population

increases over the years, these adjustment factors suggest that a typical American increased his/her

trips by 2.7% per year (Table A3.5). This rate is comparable to the 2% increase observed between

the 1969 and 1990 surveys.

The fundamental assumption in this approach is that the changes observed in the “nonaccompany” trips reflect the changes observed in all trips. The validity of this assumption is

checked by first examining how representative the “non-accompany” trips are in both 1990 and

1995. “Non-accompany” trips in both 1990 and 1995 account for no less than 50 percent of the

total person trips (Table A3.6), suggesting that using “non-accompany” trips to estimate the

magnitude of travel changes in all trips appears to be reasonable. The validity of this assumption

is further verified by checking whether the “non-accompany” rate has changed from 1990 to 1995.

More than three quarters of work trips and school trips are not accompanied by other household

members. This percentage remains relatively stable from 1990 to 1995 (Table A3.6). Note that

dropping off and picking up children from schools are not considered “school trips” they are

categorized under “Other family and personal business.” Almost all trips remain somewhat stable

for the non-accompany rate between 1990 and 1995 except social and recreational trips. There is

a smaller percentage of social and recreational trips in 1995 that went “unaccompanied by other

households” than in 1990: 49% vs. 54%. That data seem to support the idea that using only “nonaccompany” trips to estimate travel changes between 1990 and 1995 is reasonable.
2001 NHTS Summary of Travel Trends Appendix 3

A3-11 

Table A3.4. 1990 Travel Data Adjustment

(Person trips in thousands)

Purpose 1990 Trips

(1)

Adjustment

Factor

(2)

Adjusted

1990 Trips

(1) × (2)

1995 Trips Average

Annual %

Change

Work, School 82,240,011 1.00 82,240,011 110,115,282 6.01

Shopping 47,056,740 1.25 58,820,925 76,688,225 5.45

Other Fam/Per Bus 56,551,552 1.41 79,737,688 97,075,588 4.01

Social/Recreationa

l

61,799,215 1.32 81,574,964 94,361,999 2.96

Other 1,914,779 1.00 1,914,779 689,270 -

TOTAL 249,562,297 304,288,367 378,930,363 4.49

Table A3.5. Daily Person Trips per Person

Adjusted 1990 and 1995 NPTS

1990 Trip

Rate

Adjustment Factor

Diary+Rostering

Adjusted

1990

Trip Rate

1995 Trip

Rate

Average Annual

Change Rate

(%)

Work, School 1.015 1.00 1.015 1.248 4.22

Shopping 0.580 1.25 0.725 0.869 3.70

Other Fam/Per Bus 0.698 1.41 0.984 1.100 2.26

Social/Recreational 0.762 1.32 1.006 1.070 1.24

Other 0.024 1.00 0.024 0.008 --

TOTAL 3.079 - 3.754 4.296 2.73
Appendix 3 2001 NHTS Summary of Travel Trends

A3-12 

Table A3.6. One-Household-Member Person Trips, Total Person Trips,

and Non-Accompany Rate by Trip Purpose

1990 and 1995 NPTS 

(Person Trips in thousands)

Purpose

1990 NPTS 1995 NPTS

HH NonAccompany

Person Trips

Total Person

Trips

NonAccompany

 Rate

HH NonAccompany

Person Trips

Total

Person

Trips

NonAccompany

Rate

Work, School 62,973,929

27,983,544

33,237,593

33,166,604

1,233,007

158,594,677

82,240,011

47,056,740

56,551,552

61,799,215

1,914,779

249,562,297

 76.57% 84,974,961

45,996,625

58,602,172

46,509,286

356,444

236,439,488

110,115,282

76,688,225

97,075,588

94,361,999

689,270

378,930,363

 77.17%

Shopping 59.47% 59.98%

Other Fam/Per Bus 58.77% 60.37%

Social/Recreational 53.67% 49.29%

Other 64.39% 51.71%

TOTAL 63.55% 62.40%

This analysis was conducted using simple methods with the data available. These

calculations might raise as many questions as they have answered. Notwithstanding, this is the first

attempt to explain the differences on travel that can be attributed to the improvements in the survey

methods. Hopefully more research on the effects of different survey methods will follow.
2001 NHTS Summary of Travel Trends Appendix 4

A4-1

APPENDIX 4

SELECTED STANDARD ERROR TABLES
Appendix 4 2001 NHTS Summary of Travel Trends

A4-2

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2001 NHTS Summary of Travel Trends Appendix 4

A4-3

Appendix 4

SELECTED STANDARD ERROR TABLES

The final adjusted weights are used in calculating parameter estimates and their sample

variance. The standard error estimates shown in the following tables were obtained using the

replicate weight variance formula. Further information on calculating standard errors using this

method can be found in Chapter 7 of the January 2004 edition of the NHTS User’s Guide (Version

3).

The standard errors that are shown in the following tables reflect the sampling error but not

the variation in estimates due to some nonsampling errors. Sampling error is due to variability

between estimates from all other possible samples of the same size that could have been selected

using the same sample design (e.g. variation that occurred by chance because a sample was surveyed

rather than the entire household population). Estimates that were derived from any of these different

samples would differ from one another. Nonsampling error, which can sometimes be much larger

than sampling error, is not measured by the standard error.

 

The standard error of these estimates can be used to construct an interval around specific

estimates. This interval will include, with a given amount of confidence, the true population value.

About 68 percent of the intervals, created by subtracting one standard error and adding one standard

error to the specific estimate, will include the true population value. About 95 percent of the

intervals, created by subtracting two standard errors and adding two standard errors, will include the

true population value, and about 99.75 percent of the intervals, created by subtracting and adding

three standard errors, will include the true population value. Thus, one can state, with a given

percent of confidence (as stated above) that the computed interval will contain the true population

value.

An example of how these standard errors could be used is as follows. One may want to
Appendix 4 2001 NHTS Summary of Travel Trends

A4-4

know the annual person miles traveled per household for social and recreational purposes. The

estimate of the total number of annual person miles of travel per household for social and

recreational purposes in 2001 is 10,586. The standard error for this estimate, as found in Standard

Errors for Table 5, is 282.64. To construct an interval that would include the true population value

about 68 percent of the time, one would calculate: 10,586 ± (1)282.64. Therefore, a 68 percent

confidence interval for the true person miles traveled per household, as shown by this data, would

be included in the interval 10,303 to 10,869 person miles of travel per person. An interval that

would include the true person miles per household about 95 percent of the time would be

constructed by solving: 10,586 ± (2)282.64. Hence, a 95 percent confidence interval for the true

number of person miles of travel per household for social and recreational purposes is in the interval

from 10,021 to 11,151 person miles per household.
2001 NHTS Summary of Travel Trends Appendix 4

A4-5

Standard Errors for Table 1

Summary Statistics on Demographic Characteristics and Total Travel,

2001 NHTS

Standard Errors for:

 HOUSEHOLDS (000)

 All 3

 1 person 0

 2 persons 2

 3 persons 4

 4+ persons 1

 PERSONS (000)

 All Persons 5 or older 391

 Under 16 202

 16-19 336

 20-34 229

 35-64 106

 65+ 47

 All Males 5 or older 228

 All Females 5 or older 263

 LICENSED DRIVERS (000)

 All 357

 Men 237

 Women 287

 WORKERS (000)

 All 524

 Men 304

 Women 403

 HOUSEHOLD VEHICLES (000)

672

 HOUSEHOLD VEHICLE TRIPS (000,000)

1,037

 HOUSEHOLD VMT (000,000)

21,552

 PERSON TRIPS (000,000) 5+

1,539

 PERSON MILES OF TRAVEL (000,000) 5+

60,567
Appendix 4 2001 NHTS Summary of Travel Trends

A4-6

Standard Errors for Table 5

Average Annual PMT, Person Trips and Trip Length by Trip Purpose

2001 NHTS

Stderr for Avg Annual PMT per HH

All Purposes 564.13

To/From Work 97.89

Work Related Business 263.74

Shopping 105.47

All Other Fam/Per Business 173.83

School/Church 47.19

Social and Recreational 282.64

Other 266.00

Stderr for Avg Annual Person Trips per HH

All Purposes 14.33

To/From Work 4.14

Work Related Business 2.41

Shopping 6.26

All Other Fam/Per Business 7.08

School/Church 4.46

Social and Recreational 7.83

Other 1.17

Stderr for Avg Person Trip Length

All Purposes 0.16

To/From Work 0.16

Work Related Business 2.41

Shopping 0.14

All Other Fam/Per Business 0.19

School/Church 0.11

Social and Recreational 0.29

Other 8.51
2001 NHTS Summary of Travel Trends Appendix 4

A4-7

Standard Errors for Table 6

Average Annual VMT, Vehicle Trips, and Trip Length

by Selected Trip Purposes

2001 NHTS

Stderr for Avg Annual VMT per HH

All Purposes 200.79

To or From Work 69.73

Shopping 50.29

Other Fam & Personal Business 88.60

Social and Recreational 126.22

Stderr for Avg Annual Vehicle Trips per HH

All Purposes 9.66

To or From Work 3.85

Shopping 4.24

Other Fam. & Personal Business 5.05

Social and Recreational 3.95

Stderr for Avg Vehicle Trip Length

All Purposes 0.09

To or From Work 0.12

Shopping 0.10

Other Fam. & Personal Business 0.15

Social and Recreational 0.27
Appendix 4 2001 NHTS Summary of Travel Trends

A4-8

Standard Errors for Table 9

Total Person Trips by Mode of Transportation and Trip Purpose

2001 NHTS

(millions)

Standard Errors

Private Public Transit Walk Other Total 

Total

1,562 203 482 291 1,595

To or From Work

439 99 90 45 444

Work Related

Business

252 34 53 48 259

Family and

Personal Business

1,128 104 277 97 1,165

School/Church 434 60 140 170 474

Social and

Recreational

772 72 328 141 882

Other 103 24 38 42 133
2001 NHTS Summary of Travel Trends Appendix 4

A4-9

Standard Errors for Table 16

Average Vehicle Occupancy for Selected Trip Purposes

(person miles per vehicle mile)

2001 NHTS

Standard Errors

To or From Work 0.006

Shopping 0.020

Other Family or

Personal Business

0.019

Social and Recreational 0.029

All Purposes 0.010
Appendix 4 2001 NHTS Summary of Travel Trends

A4-10

Standard Errors for Table 17

Households by Availability of Household Vehicle

2001 NHTS

(thousands)

Standard Errors for Households with --

No Vehicle 181

One Vehicle 311

Two Vehicles 304

Three or More Vehicles 250

ALL 3

Vehicles Per Household 0.0063
2001 NHTS Summary of Travel Trends Appendix 4

A4-11

Standard Errors for Table 20

Number of Household Vehicles and Average Vehicle Age by Vehicle Type

2001 NHTS

Standard Errors for Vehicles (000)

 Total 672

 Auto 644

 Van 248

 Sport Utility 309

 Pickup 358

 Other Truck 67

 RV/Motor Home 71

 Motorcycle 151

 Other 88

Standard Errors for Avg Vehicle Age

 Total 0.047

 Auto 0.060

 Van 0.082

 Sport Utility 0.078

 Pickup 0.096

 Other Truck 1.107

 RV/Motor Home 0.457

Note:

! Standard errors are generated for number of household vehicles and average vehicle age, not on percentage of

household vehicles and vehicle age.
Appendix 4 2001 NHTS Summary of Travel Trends

A4-12

Standard Errors for Table 22

Average Annual Miles per Vehicle by Vehicle Age

(Vehicle Owner's Estimate)

2001 NHTS

 Standard Errors for Vehicles

 0 to 2 years 173.46

 3 to 5 years 127.39

 6 to 9 years 153.40

 10 or more years 107.24

 ALL 420.99
2001 NHTS Summary of Travel Trends Appendix 4

A4-13

Standard Errors for Table 23

Average Annual Miles per Licensed Driver by Driver Age and Gender

(Self Estimate)

2001 NHTS

Driver Age

Stderr for ALL

16 to 19 380

20 to 34 237

35 to 54 125

55 to 64 211

65+ 119

ALL 93

Stderr for Men

16 to 19 631

20 to 34 345

35 to 54 227

55 to 64 362

65+ 174

ALL 147

Stderr for Women

16 to 19 340

20 to 34 222

35 to 54 115

55 to 64 198

65+ 110

ALL 91
Appendix 4 2001 NHTS Summary of Travel Trends

A4-14

Standard Errors for Table 25

Number of Workers by Usual Mode

2001 NHTS

(thousands)

Mode of Transportation Stderr

All Modes 626

Auto, Truck, Van, or Utility Vehicle 622

Public Transit 197

Walk 159

Other 103

Note:

! Standard errors are generated for number of workers by usual mode, not on percentage of workers by usual mode.
2001 NHTS Summary of Travel Trends Appendix 4

A4-15

Standard Errors for Table 29

Daily Travel Statistics by Weekday vs Weekend

2001 NHTS

Standard Errors for Daily Travel Statistics Weekday Weekend

Vehicle Trips per Driver 0.014 0.031

Daily Work Trips 0.009 0.008

Daily Non-Work Trips 0.015 0.028

VMT per Driver 0.381 0.492

Average Vehicle Trip Length 0.106 0.185

Average Time Spent Driving (in minutes) 0.394 0.649

Person Trips per Person 0.016 0.036

PMT per Person 0.660 1.406

Average Person Trip Length (5+) 0.158 0.340
Appendix 4 2001 NHTS Summary of Travel Trends

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2001 NHTS Summary of Travel Trends Appendix 5

A5-1

APPENDIX 5

DIFFERENCES IN METROPOLITAN AREA DEFINITIONS

BETWEEN 1983 AND 1990 NPTS
Appendix 5 2001 NHTS Summary of Travel Trends

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2001 NHTS Summary of Travel Trends Appendix 5

A5-3

Appendix 5

DIFFERENCES IN METROPOLITAN AREA DEFINITIONS

BETWEEN 1983 AND 1990 NPTS

Between 1983 and 1990, the United States Office of Management and Budget changed the

definition of a Metropolitan Statistical Area (MSA). This change complicates any comparisons of

metropolitan area data from the 1983 and 1990 NPTS. In 1983 all areas were divided into

combinations of counties called Standard Metropolitan Statistical Areas (SMSAs), with the

exception that SMSAs in New England consisted of cities and towns. Typically, metropolitan areas

are redefined following each census, resulting in additions or subtractions of counties, New England

towns, and central cities. Substantial changes were made following the 1980 Census because of

considerable revisions in the standards used by the Office of Management and Budget to define the

areas.

By 1990 the term "metropolitan statistical area" (MSA) replaced "standard metropolitan

statistical area" (SMSA). An optional two-tiered metropolitan structure was introduced for MSAs

of a million people or more. These MSAs could be subdivided into Primary MSAs (PMSAs) if

certain decentralization conditions were met and if the locality desired such subdivisions. If PMSA's

were defined within an MSA, then the MSA became a Consolidated MSA (CMSA). 

Of the 318 preexisting SMSAs, 53 became PMSAs within 15 CMSAs, and 8 new PMSAs

were established within these CMSAs. In addition, 5 preexisting SMSAs became CMSAs which

were further subdivided into 10 PMSAs. As the result of these redefinitions, there were 20 CMSAs

with 71 component PMSAs when the 1990 NPTS was conducted. Among these 20 CMSAs, there

were ten with a population of more than 3 million. These ten CMSAs were made up of 48 PMSAs,

most of which did not by themselves have a population more than 3 million. Moreover, there was

one MSA in 1990 with a population of more than 3 million.

In the 1990 and 1995 NPTS, the variable MSASIZE was given a population size value based
Appendix 5 2001 NHTS Summary of Travel Trends

A5-4

on its MSA or CMSA size. Therefore, if a household was located in an area within a PMSA of less

than 3 million, but its CMSA had a population of more than 3 million, then the household was

categorized as being located in an MSA of 3+ million. In 1983 and all previous NPTS surveys,

however, only the SMSAs which by themselves had a population of more than 3 million were

categorized as being "3+ million." The implication of this definitional change on the NPTS data is

that many more households were estimated by the 1990 and 1995 data as being located within

metropolitan areas with a population of more than 3 million than that estimated by the previous

NPTS surveys.