Our Nation’s Travel:

Current Issues

2001 National Household 

Travel Survey (NHTS)
Notice

The Federal Highway Administration provides 

high-quality information to serve government, 

industry, and the public in a manner that 

promotes public understanding. Standards 

and policies are used to ensure and maximize 

the quality, objectivity, utility, and integrity of its 

information. FHWA periodically reviews quality 

issues and adjusts its programs and processes 

to ensure continuous quality improvement.
I

NHTS Web site: http://nhts.ornl.gov

User Support: Susan Liss, FHWA (202) 366-5060

 Susan.liss@fhwa.dot.gov

Nanda Srinivasan, FHWA Support (202) 366-5021 

Nanda.srinivasan@fhwa.dot.gov

Web site Support: Rick Goeltz, ORNL (865) 946-1257

goeltzrt@ornl.gov

To Obtain NHTS dataset or reports:

Federal Highway Administration

Office of Highway Policy Information, HPPI-30

NPTS Team, Room 3300

Washington, DC 20590

(202) 366-0160

This report was prepared by the Office of Highway Policy Information,

Federal Highway Administration

Source and Accuracy: All of the data presented in this report is from 

the 2001 National Household Travel Survey (NHTS), and earlier surveys 

in the National Personal Travel Survey series, unless otherwise indicated. 

Since 1990, the data from this survey were collected using random digit dial 

telephone survey of households in the United States. The survey’s estimation 

procedure uses weights to inflate the sample results to independent estimates 

of the total population of the United States. Since the NHTS estimates are 

produced from a sample survey, they are subject to two possible types of 

errors: sampling and non-sampling errors.

Sampling errors occurs because the results are based on a sample survey, 

rather than the entire population. Non-sampling errors are those errors 

resulting from survey processes and can be attributed to several sources: the 

inability to obtain information about all the cases in the sample (unit and item 

non-response); the inability to obtain accurate information from respondents; 

errors made in the data collection, such as recording and coding errors; and 

errors made in data processing.

The accuracy of the survey estimates depends on both types of error. 

Although the survey procedures are designed to minimize the impact of 

non-sampling errors the amount is still unknown. The amount of error due 

to sampling can be estimated, and when analyses are done the estimates 

should always be viewed in conjunction with the associated sampling errors. 

Users should be particularly careful when interpreting results based on a 

relatively small number of cases or when there are small differences between 

estimates. 
II 
III

Our Nation’s Travel: Current Issues

CONTENTS

Overview........................................................................ 1

Safety ............................................................................ 7

Congestion .................................................................. 14

Mobility ........................................................................ 20

Trip Chaining ............................................................... 28

Walk and Bike.............................................................. 32

Energy Consumption ................................................... 35

Future Trends .............................................................. 39

Terms Used ................................................................. 44

The 2001 NHTS dataset was collected and produced by Westat (Rockville, 

Maryland) and Morpace (Farmington Hills, Michigan)

This booklet highlights transportation issues as they relate to the daily travel of 

the American public. The 2001 National Household Travel Survey (NHTS) is the 

primary source of statistical data for this exploration, although other sources are 

used and cited. The NHTS contains data on all trips: (1) of all lengths; (2) by all 

modes, and (3) for all purposes. 

More on the conduct of the NHTS can be found in the Source and Accuracy 

Statement and at the resources listed below. 

The intent of this booklet is to briefly touch on current issues and facets of the 

transportation system that influence our daily travel behavior. The reader is 

encouraged to explore these topics further using:

• The NHTS Web http://nhts.ornl.gov - particularly the reports and the online analysis capability; and

• The NHTS CD-ROM available from the Bureau of Transportation 

Statistics, 202-366-DATA, which includes the survey data from the long 

trip section. 

Authors

This publication was prepared by:

Susan Liss, Federal Highway Administration

Nancy McGuckin, Travel Behavior Analyst

Sheila Moore, Oak Ridge National Laboratory

Timothy Reuscher, MacroSys Research and Technology.

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2001

Our Nations Travel: Current Issues 1 Overview

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2001

NOTES ON NHTS/NPTS/ATS SERIES

The 2001 NHTS, and its predecessor surveys, the 1969, 1977, 

1983, 1990 and 1995 National Personal Transportation Survey 

(NPTS), and the 1995 American Travel Survey (ATS) are the 

nation’s authoritative source of statistical data on the travel of the 

American public. The ATS collected data on long-distance trips while 

the NPTS collected mainly daily trips, with limited long-distance travel 

information. The 2001 NHTS represents a combining of the NPTS and 

the ATS. 

Attempts were made to insure that the data across the daily-trip series 

was comparable, however certain changes were required in these 

surveys over time. The reader of this publication should note: 

• The 1969, 1977, and 1983 NPTS were conducted for DOT by the 

Census Bureau as face- to-face surveys; respondents reported their 

travel by recall. 

• The 1990 NPTS was a telephone survey that used recall for 

collection of travel by household members aged 5 and over. 

• The 1995 NPTS also was a telephone survey, but used a travel diary 

to collect trip reports from every household member aged 5 and over. 

• The 2001 NHTS was a telephone survey with a travel diary used to 

collect data from every person in the household, regardless of age. 

All together, 69,817 households and 160,758 interviewed people are 

weighted to represent the travel in the U.S. 

The changes in survey methodology, for instance the switch to a trip 

diary, impacts trend analysis. Trip correction factors were developed to 

raise the 1990 trip and travel estimates to compare with 1995. However, 

no comparable factors were developed for the pre-1990 NPTS surveys. 

Details are available in the 1995 Summary of Travel Trends Report (on 

the 1995 website http://www-cta.ornl.gov/npts). 

When person-and trip-level data are analyzed, such as total person miles 

of travel, it is important to compare the same populations. In 2001, the 

inclusion of children under the age of 5 increases the base population. 

For trend analysis on persons or travel, the children under 5 in 2001 

NHTS should be excluded.

Overview
2 Overview Federal Highway Administration

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2001

TRENDS IN TRAVEL BEHAVIOR

Vehicle Ownership Continues to Rise. There is a continued 

increase in the number of household-based vehicles, and in 

households with more vehicles than drivers. In 2001, more than 

one out of five U.S. households had more vehicles than drivers. 

(see page 6)

Time Spent Driving is also on the Rise. Since 1990, the amount of 

time Americans spend driving in an average day is up 24 percent--

from 49 minutes a day to 61 minutes. (see page 19)

Very Young and Very Old Drivers Have Highest Fatalities. Using 

the vehicle miles of travel as estimated from the survey shows 

who is at-risk of a fatal accident based on the amount of travel by 

different age groups, with teens and the elderly having the most 

fatal crashes per 100 million vehicle miles of travel. (see page 8)

Other Drivers are Seen as the Biggest Threat to Safety on the 

Road. The American public has concerns about safety on the 

roads, especially aggressive, distracted and speeding drivers. 

Both women and men are concerned about other drivers, but 

women are more concerned about other safety issues than men. 

(see page 13) 

Weekend Traffic May be Greater Than Peak Period. Congestion 

used to be associated with the work trip, but as Americans keep 

adding travel for shopping and leisure, weekend travel has grown. 

(see page 14)

Trip Chaining is an Important Consideration. Over a quarter of 

workers make short stops (30 minutes or less) on their way to and 

from work for a variety of reasons, such as dropping off children, 

getting coffee, or running errands. This growing phenomenon 

impacts travel mode, route choice and often dictates departure 

time. (see page 29)
Our Nations Travel: Current Issues 3 Overview

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2001

GROWTH IN TRAVEL, 1969—2001

From 1969 to 2001, there were modest increases in the population 

and the number of households, but much more dramatic increases 

in all four measures of travel: person trips, person miles of travel 

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

significant to note that during that time period VMT increased by 

194 percent while road miles only grew by seven percent. The 

annual number of fatalities on our nation’s highways decreased 

by 20 percent—from 50,000 to 40,000 traffic fatalities per year. 

In terms of air quality, the air we breathe is actually cleaner than 

it was in 1969. There was a 43 percent decrease in carbon 

monoxide, a 59 percent decrease in volatile organic compounds 

(VOC), and a 5 percent increase in nitrous oxide (NOx).

Change in Travel-Related Characteristics, 1969 - 2001
4 Overview Federal Highway Administration

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2001

THE CHANGING AMERICAN HOUSEHOLD 

Between 1969 and 2001, there have been many changes in the 

American household—household size declined, vehicle ownership 

increased and workers and drivers per household increased. 

The most dramatic change has been the increase in vehicle 

ownership. Vehicles per household, per licensed driver, and per 

worker all grew dramatically (63 percent, 51 percent, and 45 

percent respectively). 

Trends in the Factors that Affect Travel
Our Nations Travel: Current Issues 5 Overview

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2001

WHO TRAVELS AND HOW MUCH?

The average amount of travel miles of U.S. residents varies 

considerably between people in different types of situations. A 

person in a household with income of less than $25,000 a year 

averages just under 27 miles per day (9,855 annual miles), or 

about half of the miles of a person in a household at the opposite 

end of the travel spectrum, people who travel over 58 miles a day 

(18,104 annual miles) and have education beyond a bachelor’s 

degree.

Average Daily Person Miles by Selected Characteristics
6 Overview Federal Highway Administration

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2001

 MORE AND MORE HOUSEHOLD VEHICLES 

Since 1969, the number of households without vehicles has 

declined (to about eight percent of all households), while the 

majority of households now have two or three vehicles. In 2001 

the number of household-based vehicles, 202 million, exceeded 

the number of drivers by 12 million. In fact, in 22.7 million or 21.2 

percent of all U.S. households, there are more vehicles than 

drivers. 

Some of the extra are specialty vehicles, like a motorcycle, pick-up 

truck, or the old car that the family uses when they take the dog 

along. The average age of the household vehicle fleet has been 

steadily increasing over time (from 5.6 to 8.9 years on average), 

with many observers concluding that households are keeping 

their older vehicles, rather than trading them in, when they acquire 

newer vehicles. Although personal miles of travel in vehicles 

continues to grow, household vehicles are used less intensively in 

those households where there are more vehicles than drivers.

 Households by Number of Vehicles
Our Nations Travel: Current Issues 7 Safety

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2001

WHAT IS A CRASH RATE AND WHY IS IT IMPORTANT?

Crash rates are an important tool in targeting safety 

measures, programs and campaigns. Of course, 

calculating a crash rate by age requires a survey that 

collects vehicle miles for all purposes by age group, like the 

NHTS.

A crash rate is computed to show highway accidents or fatalities 

per 100 million vehicle miles of travel (VMT). Crash rates are 

often computed by age of the driver, and based on the number 

of crashes per 100 million VMT. The importance of calculating 

the crash rate this way is that it puts accidents and fatalities into 

the context of the amount of driving done. Thus it shows a very 

different picture from the distribution of licensed drivers or of fatal 

accidents. Once the crash rate is calculated, it is obvious that the 

two groups at greatest risk are teens and the elderly. 

Percent of Vehicle Miles of Travel by Age Group

(Exposure Rate)

Safety
8 Federal Highway Administration Safety

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2001

Fatal Crash Rate: Fatalities per 100 million

Vehicles Miles of Travel

Percent of Fatalities by Age Group
Our Nations Travel: Current Issues 9 Safety

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2001

WHO IS DRIVING DURING THE HIGHEST ACCIDENT 

TIMEFRAMES?

Young men 16 to 24 average six percent of all VMT, but account 

for just over 26 percent of VMT in the high accident timeframes 

(defined as midnight to 3 a.m. on Saturday and Sunday morning 

for purposes of this chart). Young women ages 16 to 24 also have 

a disproportionately high VMT during these high-risk periods.

Percent of Vehicle Miles Driven During High Accident 

Times (mid-3:00 a.m. Sat. and Sun.)
10 Federal Highway Administration Safety

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2001

DOES WHERE YOU LIVE MAKE A DIFFERENCE IN YOUR 

SAFETY ON THE HIGHWAY?

Most fatal crashes happen on rural roads, which account for 

three-quarters of the nation’s lane miles, just under 40 percent 

(39.5) of all VMT, but 55 percent of all fatal crashes. Research 

conducted by the National Highway Traffic Safety Administration, 

NHTSA, shows that residents of rural areas have a much greater 

propensity for involvement in fatal highway accidents than their 

urban counterparts. 

(see: http://www.nhtsa.dot.gov/people/injury/research/ruralz.htm) 

Seventeen percent of drivers are from rural areas, yet they 

account for 40 percent of all fatal crashes. Given this pattern, it 

is useful to understand the differences in the profile of urban and 

rural drivers and their travel. 

Average Annual Miles per Driver
Our Nations Travel: Current Issues 11 Safety

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2001

This summary points to several reasons that rural residents are 

at greater risk for involvement in fatal accidents. They tend to 

drive 3,100 more miles each year, or 25 percent more than their 

urban counterparts. Generally, rural residents must travel longer 

distances for all purposes of trips. 

Perhaps the most significant factor that is typically not highlighted 

is that rural residents have older vehicles—on average, a year 

older than those owned by urban households. 

The age of a vehicle not only affects it functioning, but may also 

indicate fewer safety features, such as air bags. 

 

Average Vehicle Age
12 Federal Highway Administration Safety

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2001

WHAT DOES THE PUBLIC THINK ABOUT SAFETY 

ISSUES?

The NHTS asked the American public their level of concern for the 

following:

• aggressive drivers 

• distracted drivers

• drunk drivers 

• speeding drivers 

• number of large trucks on the road, and

• worry about traffic accidents.

Aggressive and distracted drivers are perceived as the greater 

threats to safety, followed closely by speeding drivers.
Our Nations Travel: Current Issues 13 Safety

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2001

ARE THERE GENDER DIFFERENCES IN CONCERN 

ABOUT SAFETY ISSUES?

In each safety issue under consideration, women consistently 

showed more concern than men. Gender was one of the few 

attributes that showed consistent differences. Concern about 

safety issues did not follow any clear pattern by household 

income, population size or population density of the area of 

residence, or race of the household respondent.

Percent of Men and Women Very Concerned 

About Safety Issues
14 Federal Highway Administration

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2001

Congestion 

ARE WE SEEING MORE CONGESTION AT OFF-PEAK 

PERIODS? 

Congestion used to be associated with just work trips, but 

most roadways are carrying more shopping, errands, and 

social/recreational travel, especially those serving regional 

malls or recreational areas. Weekend traffic may be as bad as any 

weekday. Overall, Saturday at 1:00 p.m. has a higher number of 

vehicle trips than either the morning or afternoon peak periods on 

a typical weekday (Wednesday).

Number of Vehicle Trips by Time of Day

Congestion

Note: Includes all trips made on a Wednesday or Saturday 

throughout the year.
Our Nations Travel: Current Issues 15

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2001

Congestion

IS CONGESTION ONLY A PROBLEM IN BIG CITIES?

Most research shows that congestion is worse in the largest metro 

areas, but it is certainly not exclusive to big cities. To equalize 

differences in trip lengths among areas, the following table shows 

trip duration in minutes for private vehicle trips of 10 miles only. 

Travel time for a 10-mile trip does increase as area size increases, 

but a larger determinant seems to be the density of population.

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Population Density

Average Duration of a 10-Mile Vehicle Trip (In Minutes)
16 Federal Highway Administration

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2001

Congestion 

HOW MUCH OF A PROBLEM IS CONGESTION?

The NHTS asked respondents how much of a problem congestion 

was in their life. Almost half (49.3 percent) of the survey 

respondents reported that congestion was not a problem or a little 

problem. Those that gave this response are largely older (65+) or 

younger (16 to 19), not working, and living in rural or small towns. 

Only 28 percent overall said congestion was very much or a 

severe problem.

A severe 

problem 

13% Not a 

problem 

40%

Very much 

of a problem 

11%

A little 

problem 

17%

Somewhat 

of a problem 

19%

However, for those people living in the largest metro areas (three 

million or more in population) only 37.2 percent said congestion 

was not a problem or a little problem, with just slightly more (39.5 

percent) saying it was very much or a severe problem.
Our Nations Travel: Current Issues 17

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2001

Congestion

WHO CONSIDERS CONGESTION TO BE “VERY MUCH 

OR A SEVERE” PROBLEM?

Only 28 percent of the respondents asked this question said that 

congestion was very much of a problem or a severe problem. 

This average did not vary consistently by demographic factors or 

geographic location. Those who consider congestion to be very 

much of a problem or a severe problem follow certain expected 

patterns, such as living in the largest metro areas, but also 

include the unexpected, like motorcycle drivers and RV drivers. 

At the opposite end of the spectrum, who is least bothered by 

congestion, there are a few surprises, including 16 to 19 year-olds, 

a group never known for their patience. 

Percent Responding that Congestion was a 

Major or Severe Problem
18 Federal Highway Administration

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2001

Congestion 

IS THERE A CONNECTION BETWEEN ATTITUDES 

ABOUT CONGESTION AND THE AMOUNT OF TIME 

SPENT IN TRAVEL?

People who view congestion as a major or severe problem spend 

more time in travel than those less bothered by congestion. 

Attitude About Congestion by Income

Attitude About Congestion by MSA Size
Our Nations Travel: Current Issues 19

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2001

Congestion

HOW MUCH OF THE EXTRA TIME SPENT IN VEHICLES 

IS TO GO MORE MILES?

Between 1990 and 2001, the average driver increased their daily 

distance by 4.2 miles, and increased their driving time by almost 

12 minutes. 

Since 1995, it appears as if travel time is growing faster than travel 

miles. While miles per driver increased 15 percent between 1990 

and 2001, the amount of time the average driver spends in the 

vehicle increased by 24 percent.
20 Federal Highway Administration

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2001

Mobility 

WHAT ARE THE MOST IMPORTANT FACTORS 

INFLUENCING THE AMOUNT OF TRAVEL?

I

t has long been recognized that two of the most important 

factors in the amount of travel are household income and 

location. As expected, travel increases as household income 

increases and travel increases as we move from urban to 

suburban to rural settings. It appears that the spread within 

income groups in the same area type is greater than the spread 

between area types within the same income group. Perhaps 

income is the stronger influence on the amount traveled.

Daily Person Trips per Person Indexed to Average

Mobility
Our Nations Travel: Current Issues 21

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2001

Mobility

EVERYBODY TRAVELS MORE – GENDER AND 

EMPLOYMENT STATUS 

At a time when average annual miles increased for all drivers by 

34 percent, employed women’s driving increased by 54 percent 

and driving by women not employed increased by 49 percent. 

There were some gains in the female driver rate between 1983 

and 2001, particularly in women not employed. In 1983, 64.2 

percent of that group were drivers, and by 2001 that rose to 75.5 

percent.

Mobility by Gender and Employment Status

Average Annual Miles Driven by Gender and 

Employment Status
22 Federal Highway Administration

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2001

Mobility 

HOUSEHOLD LIFECYCLE CHANGES OVER TIME

The stages of a person’s life, from young and single to married 

with children to retired, is referred to as “lifecycle”, and has been 

effectively used to explain and understand travel behavior. The 

lifecycle categories used with the NHTS data differentiate by 

number of household adults, presence or absence of children, age 

of the youngest child and whether the adults consider themselves 

retired. When comparing the 1983 and 2001 households by 

life-cycle, the most striking change is the increase in retired 

households, which reflects the aging of the American population.

Percent of Households by Lifecycle
Our Nations Travel: Current Issues 23

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2001

Mobility

HOW MANY PEOPLE HAVE TRANSPORTATION 

DISABILITIES AND WHAT IS THE IMPACT ON THEM?

The NHTS defines “transportation disability” as a medical 

condition that makes it difficult to travel outside the home. 

To avoid temporary conditions, like a cast on a broken leg, a 

threshold is established that the condition must have existed for at 

least 6 months.

Overall 16.5 million people or 6 percent of the NHTS sample has a 

transportation disability—but that is highly linked to age. Only 3.7 

percent of people under the age of 65 (nine million people) have 

a disability, whereas 22.5 percent of people 65 and older do (7.5 

million).

Overall, a transportation disability means that people reduce their 

travel, ask others for rides, or limit driving to daytime. There is 

a reluctance to give up driving altogether, although nearly eight 

percent of older people with a transportation disability have given 

up driving. 

* Note that the same person can select several impacts
24 Federal Highway Administration

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2001

Mobility 

WHAT ARE THE SPECIAL MOBILITY ISSUES OF OLDER 

AMERICANS?

As we age, our vision, cognitive function, reaction time and 

psychomotor abilities tend to decline. All of these issues may 

lead to a loss of mobility, which can subject an older person to a 

loss of social interactions. One of the most difficult transitions for 

older drivers is the decline or cessation of travel at night or in bad 

weather. Typically this leads to giving up driving all together, and 

many of the factors that cause an older person to give up driving 

also inhibit or prohibit their use of other travel modes, such as 

transit or walking.
Our Nations Travel: Current Issues 25

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2001

Mobility

DO OLDER WOMEN HAVE SPECIAL TRAVEL 

PROBLEMS? 

Older women (65+) experience greater mobility issues because:

• Women of all ages tend to travel less than their male 

counterparts

• Many older women today did not grow up driving

• Women outlive men and are often widowed and living 

alone for many years

• Older women often have greater concerns than older men 

about their personal safety and security.

To take a different look at the mobility issues of older women, the 

chart below shows the percent of women who did not make a trip 

on their assigned survey Travel Day. While the assigned Travel 

Day may or may not have been a typical day for any given survey 

respondent, on average, it provides a representative look at daily 

travel in the United States.

Twelve percent of all persons, men and women, did not report a 

trip on the travel day, but 77 percent of those who did not travel 

were 75 years of age or older. The average zero-trip rate for 

all women is 13.7 percent. The chart confirms a few expected 

outcomes:

• Women 65 and older are more likely to not make a trip 

than women under 65.

• The prevalence of zero-trip making increases with age, 

and shoots up dramatically for those 85 and older.

• The differences in zero-trip days between urban, suburban 

and rural/small town women may be due to differences in 

household income.

Accordingly, the next graph shows the impact of income on the 

percent of zero-trip women. Within each age grouping, there is 

a very strong correlation between income and zero-trip making. 

As income rises, the incidence of zero-trip making decreases. 
26 Federal Highway Administration

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2001

Mobility 

Unfortunately, almost half (47 percent) of the women 65 and older 

were in households with incomes of less than $25,000, another 35 

percent were in households with incomes of $25,000 to $49,999, 

and only 18 percent were in households with incomes of $50,000 

or more.

Percent of Zero-Trip Women Within Each 

Age Group by Urban, Suburban, and Rural

Percent of Zero-Trip Women Within Each 

Age Group by Income
Our Nations Travel: Current Issues 27

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2001

Mobility

WHAT ABOUT HOUSEHOLDS WITHOUT VEHICLES—

WHO ARE THEY AND HOW DO THEY GET AROUND?

Zero-vehicle households account for 8.1 percent of all U.S. 

households—down from 15.3 percent in 1977. These households 

are primarily urban—7.8 million urban households and 850,000 

rural households have no vehicles available.

Over half of zero-vehicle households are located in large metro 

areas (three million or more in population). Of the zero-vehicle 

households in areas of three million or more, 67 percent had 

annual income of $25,000 or less, and only seven percent had an 

income of $75,000 or more.

Well over half (58.3 percent) of zero-vehicle households are oneperson households, compared with the average of 25.8 percent of 

all households.

People in zero-vehicle households travel differently than those 

who have vehicles—while zero-vehicle households comprise 8.1 

percent of all households, they make almost half (46.8 percent) of 

all transit trips. Their high level of transit use is also related to their 

location in the largest metro areas.
28 Federal Highway Administration

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2001

Trip-Chaining 

WHAT IS TRIP CHAINING?

The phenomenon of trip-chaining—linking a series of short 

trips (stops of 30 minutes or less, such as to stop at a store 

or to drop kids at school or day care)—into the commute to 

or from work complicates our understanding of the typical journey 

to work. 

The Census does not ask about regular stops during travel to 

work, which can impact departure time, travel time, and route 

choice. 

For at least the past 25 years transportation planners have 

focused on the commute as one of the major organizing elements 

of household travel. Commute trips are often thought to be highly 

repetitious, and therefore highly predictable. In actuality, commute 

trips vary in length and time by day and direction, and trip chaining 

impacts commuters’ departure time, route choice behavior, and 

miles traveled to work. 

Example of Trip-Chaining

Trip-Chaining
Our Nations Travel: Current Issues 29

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2001

Trip-Chaining

WHO IS TRIP-CHAINING?

In 2001, nearly 19 million weekday workers (27 percent of 

all weekday workers) chained trips as part of their commute 

compared to 17.3 million in 1995 (25 percent of weekday 

workers). Over 1.5 million more weekday workers made short 

stops during their commutes in 2001 than in 1995—almost all of 

them added stops in the home-to-work direction of the trip which 

had a 21 percent increase, while the people who chained trips in 

both directions increased by over 12 percent.

Source: McGuckin, Zmud and Nakamoto

Number of Weekday Workers by Chain Type
30 Federal Highway Administration

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2001

Trip-Chaining 

DO WORKERS WHO TRIP-CHAIN HAVE LONGER 

COMMUTES?

Workers who chain trips into the commute live farther from work, 

and travel more miles and minutes than those who do not trip 

chain. Comparison of the commute distance can be measured 

by the sum of miles traveled to work on a weekday, the reported 

distance to work, and the geocoded great circle distance (as the 

crow flies). 

The VMT for those who trip chain was much higher than the 

reported usual distance to work, whereas for workers who made 

a direct trip the actual and reported miles are virtually the same. 

Workers who chained during their commutes spent 15 to 20 

minutes longer in travel than workers who did not.

Source: McGuckin, Zmud and Nakamoto

Mean Distance in Miles Between Home and Work—

Workers who Trip Chain and Workers Who Don’t 
Our Nations Travel: Current Issues 31

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2001

Trip-Chaining

WHY DO WORKERS STOP?

By far the most common purpose for stops, within trip chains on 

the way home from work, was to shop—such trips include both 

discretionary and household-sustaining activities. The detailed 

purposes collected in 2001 NHTS include a separate coding for 

buying gasoline and meals/coffee, which are shown separate from 

other shopping in the graph. 

For workers who made stops in either direction, the most common 

type of trip embedded in the home-to-work chain was a serve 

passenger trip (35 percent), followed by family or personal 

business (16 percent) and stop for a meal or coffee (14 percent). 

For the work-to-home chain, the most common type of embedded 

trip was a shopping trip (36 percent), followed by serve passenger 

(24 percent) and family or personal business (22 percent).

Percent of Stops During Commute by Purpose
32 Federal Highway Administration

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2001

Walk and Bike 

WHAT ARE THE PURPOSES OF WALK AND BIKE 

TRIPS?

Social and recreational purposes, primarily exercise, 

dominate walk and bike trips for older teenagers and adults 

(these data are for respondents 16 and older). Over a third 

(35 percent) of all walk trips are for social and recreation, while a 

quarter are for family and personal business. 

Nearly half of all bike trips are for social and/or recreational 

purposes, and one out of six (16 percent) are for commuting 

to work. The average bike trip to work is 2.9 miles one-way, 

compared to 12.1 miles by all modes. 

The survey also asked for the number of walk and bike trips made 

during the previous week for people 16 and older. This was asked 

to get a better sense of typical walk and bike patterns, since such 

a trip may not show up on the specific travel day assigned to 

the respondent. The data on the next page provides a profile of 

frequency of walking.

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Walk and Bike
Our Nations Travel: Current Issues 33

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Walk and Bike

Number of Walk Trips in Previous Week for 

Persons 16 Years and Older

Number of Annual Walk Trips for Persons 5 to 15 

Years Old

Population Density per Square Mile
34 Federal Highway Administration

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Walk and Bike 

WHAT PORTION OF WALK AND BIKE TRIPS ARE TAKEN 

IN DAYLIGHT AND IN DARK?

Young people ages 16 to 24 make over a third (33 percent) of their 

walk and bike trips at night, while older people (65+) make the 

lowest share (17 percent).

Everyone above the age of 15 seems to average about 90 

daytime walk trips per year, or one trip every four days. As 

expected, children age five to fifteen average most walk and bike 

trips, since this represents a primary mode of their mobility.

Number of Nighttime (6PM to 6 AM) Walk and Bike 

Trips by Age

Number of Annual Walk and Bike Trips per Person 

by Age and Daytime—Nighttime
Our Nations Travel: Current Issues 35

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2001

Energy 

Consumption

HOW MANY HOUSEHOLD-BASED VEHICLES ARE SUVs 

and PICK-UPs AND HOW MUCH MILEAGE DO THEY 

ACCOUNT FOR?

Over half of the U.S. fleet is comprised of passenger cars. 

The average car is a little bit older than the average van 

or sport utility vehicle, (SUV), and accrues fewer miles per 

vehicle per year. Pick-ups are, on average, the oldest vehicles 

in the fleet—almost one year older than the average car and 

three and one-half years older than the average SUV. SUVs 

are 12 percent of all vehicles but account for 14.1 percent of all 

household based VMT, while pick-ups, which are 18.4 percent 

of the fleet, account for 19.5 percent of the total annual miles for 

household-based vehicles. 

Note: We wish to thank the Energy Information Agency, U.S. 

Department of Energy, for appending the fuel efficiency data 

(mpg) and gas cost to the 2001 NHTS dataset. The fuel costs 

used are based on May 2001-May 2002. 

Energy Consumption
36 Federal Highway Administration

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2001

Energy 

Consumption

HOW IS ANNUAL FUEL EXPENDITURE RELATED TO 

INCOME AND LOCATION?

Fuel use and annual fuel cost for a household is a function of how 

many vehicles the household has, how many miles those vehicles 

are driven, and how much motor fuel costs in the household’s 

location. 

In 2001, wealthier households ($75,000 a year and more) spent 

more in motor fuel—more than two and one half times—than 

poorer households (less than $25,000) spent; $1,749 compared 

to $662 per year. Wealthier households have more vehicles and 

accrue more annual miles. But the average varies by the location 

of the household; the wealthiest rural households spent $2,163 

per year (with an average of 2.9 vehicles) compared to the 

wealthiest urban households that spent $1,188 with an average of 

1.9 vehicles. 

Household Fuel Expenditures per Year
Our Nations Travel: Current Issues 37

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2001

Energy 

Consumption

DOES LOCATION AND INCOME AFFECT THE MILES 

PER DOLLAR OF GAS?

Looked at another way, the person miles per dollar of gas relates 

the mix of fuel-efficient vehicles in poorer and richer households 

and in rural and urban areas. Poorer urban households, with fewer 

and more efficient vehicles, get more miles per dollar of gas than 

households in other area types. Wealthier households, regardless 

of location, get fewer miles per dollar spent in fuel cost. 

Miles per Dollar of Household Fuel Expenditure
38 Federal Highway Administration

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Energy 

Consumption

HOW MUCH DO PEOPLE SPEND GOING TO WORK 

COMPARED TO OTHER TYPES OF TRIPS?

How much an average work or shopping trip costs depends on 

the type of vehicle usually used and the average trip distance. The 

average work trip, for instance, is nearly 12 miles, whereas an 

average shopping trip is only seven. Therefore, over all vehicles 

for all trip lengths, fuel costs 78 cents for the average vehicle trip 

to work but only 44 cents for the average vehicle trip for shopping.

Fuel Costs for Common Trips by Vehicle Type

P-U = Pickup Truck

SUV = Sports Utility Vehicle
Our Nations Travel: Current Issues 39

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2001

Future Trends

Changes in society, technology, and economic conditions 

will interact with lifestyle elements of travel behavior to 

continue to alter daily travel. As the population ages, we 

don’t know what the effect on the purpose and time of day of travel 

will be. Some of the visions of the future include smart growth and 

Intelligent Transportation Systems (ITS) to mitigate the impact 

of the growth in travel. Future transportation improvements will 

not likely come from large capital investments as much as from 

carefully crafted programs that include integration of policy goals, 

creative analysis and innovative solutions.

Societal and Demographic Trends

Demographic changes in the U.S. can affect travel, such as 

the added longevity and an aging population, migration and 

immigration, household structure and family definitions. 

One example of a demographic shift is the growth of single person 

households. Over a quarter of all U.S. households are singleperson households, but they are the fastest growing segment. 

Of the 13.5 million added households between 1990 and 2000, 

4.7 million were single-person households. The Census 2000 

was the first time the proportion of single-person households 

(25.8 percent) was greater than the proportion of nuclear families 

(married couples with children account for 24.3 percent).

Household size and composition have a major influence on travel. 

For example, single-person households are more likely to eat 

out. The shift from traditional nuclear families (two parents and 

children) to more diverse and smaller households adds to the 

number of people separately traveling to work, the grocery store, 

and for errands and social purposes. For instance, in 1990, three 

out of four carpools to work consisted of people from the same 

household, which rose to four out of five in 2001. 

Future Trends
40 Federal Highway Administration

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Future Trends 

The aging of the driving population in the US has raised many 

safety concerns, particularly focused on elderly driver’s declining 

vision and ability. Thirteen percent of the U.S. population is 

65 years and over, and the proportion of older Americans is 

projected to grow to 20 percent in the next three decades. The 

coming population bubble of these senior drivers is important to 

understand for both policy and safety considerations. 

Even if older drivers follow historic patterns and reduce their 

daily travel, the sheer number of added travelers will significantly 

increase the proportion of national VMT accounted for by older 

drivers. Just from the impact of the greater population, the miles 

driven by 60 to 64 year-olds could increase 25 percent in the next 

decade, while the miles driven by 65 to 69 year-olds could grow 

10 percent. 

Other societal and lifestyle factors, such as the growing 

dominance of multiple-service retail stores, where diverse goods 

and services such as clothing and dry goods, fresh produce, 

ready-meals, movie rental, and auto parts can be found in the 

same location, also impact travel. On-line services continue to 

become more common, and are changing the amount and nature 

of home deliveries. 

Technological Innovations

Throughout history more communication has led to more travel, 

and we are in an era of communication technology advances. 

Some researchers believe that people may forgo travel through 

working at home and internet shopping. But reducing travel for 

work and shopping may lead people to increase travel for other 

purposes, such as errands or recreational trips. The NHTS shows 

that workers who go to work on the travel day make an average of 

3.6 trips for all reasons whereas workers who do not go to work on 

the travel day make 4.8.
Our Nations Travel: Current Issues 41

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Future Trends

The character of working at home has changed dramatically over 

the last half century. The decline in home-based employment from 

1960 to 1970 was presumably a result of vanishing family farms 

and consolidation of professions (Doctors, Veterinarians, Lawyers) 

into group practices. But the decline has reversed, according 

to the U.S. Census, since 1980, “work at home” has increased 

almost two-fold—from 2.2 million workers to 4.2 in 2000.

The NHTS asks respondents whether they sometimes work at 

home instead of going into their regular work place—about 10 

million workers out of 145 million in the country do sometimes 

work at home (about four percent). More than six out of ten 

people who answered ‘yes’ were in professional or technical 

occupations, more often men than women, and slightly older than 

workers who did not work at home. 

Working from home is much more common in the large cities 

and less so in smaller and non-metro areas, and not surprisingly 

90 percent of the workers who occasionally work at home are 

frequent web users. People who occasionally worked at home 

instead of going to their regular workplaces had commutes 

nearly 25 percent longer than those who never worked at 

home. The growing flexibility of work, coupled with the power 

of communications technology has potential effects on miles of 

travel, congestion, and the time-of-day of travel that are still being 

studied.

Technology innovations affect more than communications 

and work—they are already present in the infrastructure with 

intelligent transportation systems (ITS). Electronic toll collection, 

traffic-enforcement through vehicle tag recognition, Global 

Positioning System (GPS) tracking of buses and snowplows, and 

variable message signs are all part of the daily landscape. HighOccupancy or Toll (HOT) lanes are an innovation that allows a 

solo driver to pay a toll to use the less congested carpool lanes. 

Fees can be collected electronically and dynamically adjusted 

based on the volume of traffic in the carpool lane to ensure that 
42 Federal Highway Administration

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2001

Future Trends 

these lanes are free-flowing at all times. This type of facility is 

being studied around the country, and HOT lanes have found 

unexpected markets, such as women with children who will pay to 

reduce travel time and increase reliability. 

Land Use

There has been a tremendous growth of population, workplaces, 

and travel in suburban areas. The continued development of 

suburban areas changes the geography and time-of-day patterns 

of congestion, including peak spreading and weekend congestion. 

Sprawling development increases auto-dependency. Much of 

today’s travel is suburb to suburb, with widely dispersed origins 

and destinations that make transit less efficient. 

The effect of greater distance between where we are and where 

we want to go significantly affects our daily lives—there has been 

an explosion of people who drive alone to work, for instance. 

Moving to a private vehicle may have saved travel time in the early 

days of suburban growth but travel time to work has increased 

in the last decade in every large metro area. On an average 

weekday, workers spend 45 minutes in their commutes out of 

100 minutes in all travel. But trips for non-work activities are 

increasing even faster than work trips—there is more travel for 

family and personal errands, shopping, and social and recreational 

purposes. Reversing an historic trend towards faster travel, the 

estimated speed for all trips is slowing.

Transportation and land-use are linked, but few opportunities exist 

for them to be integrated in the development process, which can 

result in a mismatch between transportation goals and developing 

land-use patterns. Transportation planning is carried out by both 

local and regional organizations, and coordinated through the local 

Metropolitan Planning Organization. Independent municipalities 

and organizations with no single coordinating agency, on the other 

hand, generally carry out land-use decisions. 
Our Nations Travel: Current Issues 43

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Future Trends

With smart integration of land-use and transportation planning 

many cities are seeing resurgence in urban lifestyles. Cities are 

working hard to maintain the centrality of employment centers, 

and offering a mix of social, cultural and recreational activities 

combined with renewed residential land-use. 

Smart Growth advocates see transit-oriented development, 

higher-density settlement, and discouraging the use of the auto, 

as integral to the future of our cities. Health advocates are trying to 

get Americans out of their cars to walk more every day. Mandated 

air-quality standards and increased energy use in sprawling urban 

areas create the need to assess the impact of broad-ranging travel 

demand management (TDM) strategies on American’s daily travel.

Summary 

The mobility of the majority of the American population is greater 

then ever. Moving forward, demographic shifts, technology, and 

good planning practices and strategies, are sure to change the 

nature of the transportation environment. There are still people 

who have constrained mobility, for those who are older, poorer, 

have transportation disabilities or are without access to a vehicle, 

may feel disenfranchised from the social, political, and economic 

benefits of this society. 

Mobility is part of our culture, the American dream. It is the 

fabric of our daily lives that weaves the connection between 

where we are and where we want to be. A secure and efficient 

transportation system is central to our economic well being. The 

information presented in this booklet gives a snapshot of personal 

mobility in America, and the data and publications 

(http://nhts.ornl.gov) allow policy-makers and researchers to use 

this rich source of information about household travel. To the 

extent that this snapshot has raised more questions on this topic, 

it has been a success.
44 Federal Highway Administration

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Terms 

TERMS USED IN THIS PUBLICATION

Means of Transportation – The type of transportation used for 

the trip, sometimes called “Mode.” For purposes of this report, 

any means not specifically identified on a chart will be included in 

“other.”

Privately Owned Vehicle (POV) – Motor vehicles owned by 

or available to the surveyed household. Includes cars, vans, 

sport utility vehicles, pickup trucks, other trucks, recreational 

vehicles, motorcycles and other household-based vehicles.

Public Transportation – Includes bus, subway or elevated 

rail, commuter train, and streetcar or trolley car.

Other Modes – includes walk, bicycle, school bus, airplane, 

Amtrak, and taxi.

Person Trip – A movement from one address to another by one 

person by any mode.

Person Trip by Private Vehicle – A subset of all person trips, to 

include only those trips by private vehicle. There is still one person 

trip for each person on the trip, whether they are the driver or a 

passenger.

Person Miles – The number of miles traveled by each person on 

the trip. For example, two people making a five-mile trip by car 

would generate 10 person miles.

Trip Chaining – This refers to making stops of 30 minutes or less, 

such as to drop a child at school, on the way to or from a major 

destination, such as home or work. 

Trip Purposes – A trip purpose is the reason that motivates the 

travel. In the NHTS some of the purposes are grouped into a main 

purpose, as shown below:
Our Nations Travel: Current Issues 45

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Terms

Work – Trips to and from your place of work, or where you 

report to work.

Work-related –Trips made for your job, other than travel 

to your place of work. This may include going to a meeting, 

travel to various construction sites, or visiting clients.

Family and Personal Business:

Shop –Includes purchase of goods or windowshopping.

Doctor/Dentist –Trips to doctors’ or dentists’ offices, 

medical clinics, hospitals, counselors, etc. to obtain 

medical or dental services.

Pickup/Dropoff –Trips to take someone else 

somewhere, such as picking up a child at school. This 

is sometimes called ‘Serve Passenger’.

Other Family and Personal Business –Trips for 

purchase of services, such as haircuts, banking, 

car repair, etc. and all other family and personal 

business activities that do not fall into one of the other 

subcategories above.

School/Church –Trips to schools, colleges or universities to 

attend class, or to attend religious activities.

Social and Recreational:

Vacation –Trips the respondents reported as their 

“vacation.”

Visiting Friends or Relatives–Trips specifically made 

to visit.

Other Social and Recreational –All other trips for 

social and recreational activities, including participating 

in sports, going to movies, plays, and parties, attending 

sporting events, etc.

Other –Trips that cannot be classified in any of the 

categories above.
46 Federal Highway Administration

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Terms

Vehicle Miles of Travel (VMT) – Each mile traveled by a 

household-based private vehicle. For example, two people making 

a five-mile car trip would generate five vehicle miles of travel. The 

estimates do not include transit vehicle miles because the sample 

is households, people, and household-based vehicles, which we 

track with the vehicle trips people make throughout the day.

Vehicle Occupancy – For the NHTS data, vehicle occupancy is 

calculated by weighting the number of vehicle occupants, by the 

trip length and dividing by the vehicle miles, this produces the rate 

of person miles over vehicle miles.

Vehicle Trip – Each time a private vehicle goes from one address 

to another for a purpose, a vehicle trip is counted, regardless of 

the number of the people in the vehicle.



Publication No. FHWA- PL-05-015