Chapter I. The Next Generation of Personal Travel

Who knows about kids these days? Today’s teens are members of the first generation to have never known a world without instantaneous and nearly ubiquitous mobile phone access. They must surmount greater hurdles to driver’s licensing than any previous generation faced. And they are struggling to transition into the most unwelcoming job market since the Great Depression. These tectonic happenings surely augur equally dramatic changes in the travel choices and patterns of young adults in the years ahead. Or will they? This report examines this question.

While scholars have studied the travel choices and patterns of adults extensively over the years, our knowledge of youth travel behavior is surprisingly limited and uneven. There is a growing body of research on how children travel to school (i.e., McDonald, 2007, 2008; McMillan et al., 2006; Schlossberg et al., 2006; Yarlagadda and Srinivasan, 2008), much of it linked to rising childhood obesity and the decline in so-called “active travel” among children. This is an important area of study, but it addresses only a small portion of travel by youth. Data from the 2009 American Community Survey show that less than 35 percent of young adults (16–30) attend school; the remainder—almost 37 million people—are not in school. A second body of travel research relevant to youth focuses on travel safety, and, in particular, the high rates of crashes and driving fatalities among teenagers (i.e., Goodwin and Foss, 2004; Hedlund et al., 2003; McCartt et al., 2010; Williams and Shults, 2010; Williams, 2012).

Beyond these two rather focused lines of inquiry, studies of travel by children, teens, and young adults are rare. The little information that we have suggests that while, like adults, most youth travel by automobile, their patterns of automobile travel differ from those of older adults, and these differences might be waxing. For example, teens tend to obtain driver’s licenses at later ages than in previous years. In 1995, 59 percent of 17-year-olds had driver’s licenses. By 2009, less than half (49%) were licensed (Federal Highway Administration, 1995 and 2009). Further, youth (16-30) tend to drive slightly fewer miles than adults (31-55) and have lower average daily trip rates (Booz, Allen, and Hamilton, 2011).

Researchers have posited several factors to explain differences in the travel behavior of youth and adults, and to support the argument that such differences may persist as today’s youth move into adulthood. First, the rapid profusion and adoption of new communication technologies influences how people use their time and may affect how much they travel (Hjorthol, 2002; Kwan, 2002; Mokhtarian and Salomon, 2002; Viswanathan and Goulias, 2001), and youth tend to be early and frequent adopters of these technologies (Mans et al, forthcoming; Lenhart et al., 2005; Pew Research Center, 2010b). Second, all 50 states have now adopted graduated driver’s licensing programs, making teen licensing more difficult and restrictive (with respect to time, trip purpose, and passengers) than in previous eras (Insurance Institute for Highway Safety, 2012). Third, unemployment rates during the current recession are highest for youth, thereby reducing journey-to-work and work-related travel and limiting the resources teens and young adults have to pay for non-work activities (and associated travel) of all types. This prolonged economic downturn may also influence youth travel patterns indirectly; fragmentary evidence suggests that young adults struggling to find work increasingly “boomerang” back home to live with parents (Pew Research Center, 2010b), drawn by a free or steeply discounted bedroom, groceries, and, perhaps, access to parents’ cars.

To explore the influence of these and other factors on the travel behavior of youth,¹ we use data from the 1990 Nationwide Personal Transportation Survey (NPTS) and the 2001 and 2009 National Household Travel Surveys (NHTS) to examine three specific questions:

1. How does the travel behavior of youth compare to that of adults?
2. Are the basic determinants of youth travel behavior changing?
3. Given (1) and (2), do we see evidence that as today’s youth age into adulthood, they are likely to travel differently than adults of today?

To answer these three questions we focus on four fundamental outcome measures of travel: (1) personal miles traveled (PMT), (2) activity participation (number of daily trips), (3) journey-to-work (or commute) mode, and (4) travel mode used for social trips. In analyzing each of these outcome measures, we employ a set of statistical models to assess the influence of three types of effects on travel:

1. Life cycle effects are those associated with particular stages of the life cycle and which typically do not “follow” people through the various stages of life. For example, parents with young children and retirees tend to exhibit travel patterns consistent with their particular life cycle stage.
2. Period effects are events, such as the current recession, that affect all population groups but may affect one population, in this case youth, more than others.
3. Cohort effects are the opposite of life cycle effects in that they “follow” groups of similarly situated people through time. For example, women three-quarters of a century ago were much less likely than men to get driver’s licenses, and these lower licensing and driving rates persisted throughout their lives.²

In a nutshell, we find that economic factors—employment status, household income, and the like—strongly influence the travel behavior of both adults and youth, the latter of which has been harder hit by our current, prolonged economic downturn. These economic effects help to explain the growth in mobility, trip-making, and driving among both youth and adults during the 1990s, and the subsequent contraction of mobility, trip-making, and driving during the 2000s. When it comes to changes in youth (and adult) travel behavior in recent years, the adage “It’s the economy, stupid” appears to hold.

With regard to the effects of young adults “boomeranging” to live at home with parents, the explosion of information and communications technologies, and stricter driver’s licensing requirements for teens, the effects are far milder, and mixed. While more young adults appear to be living at home than in years past, the effects on travel behavior are mixed at best. Likewise, despite the staggering increase in mobile phone and web access and use, the effects we were able to measure were both mild and tended to be associated with increases in travel. That is, when information and communications technologies affect travel, it is as a complement to travel and not a substitute for it. Finally, while teen licensing requirements have grown considerably stricter over the past two decades, and more teens are obtaining their licenses in their late teens and early twenties, the effects on overall teen mobility are surprisingly muted. Sixteen- and 17-year-olds are driving less, but they appear to be (eventually) getting driver’s licenses and moving about as much as earlier generations of adults.

Our quasi-cohort analysis suggests that there may be some moderate generational changes afoot. Despite (or perhaps because of) what appears to be an increasing reliance on the single-occupant vehicle among the youngest cohorts in our datasets, our models suggest a moderate decrease in trip-making (-4%) and a stronger effect on miles traveled (-18%) for those born in the 1990s. However, as our datasets comprise only a small “window” (1990-2009), we urge caution in interpreting these results. Further analysis with additional data years will allow researchers to test whether these trends are indeed robust.

Perhaps the most significant overall finding from this analysis is how little teen and youth travel behavior is deviating from that of adults, given the enormous economic, social, technological, and policy changes over the past two decades. Specifically, we see little evidence in these data that living circumstances, technological innovations, or driving regulations are dramatically altering travel behaviors. We do find that economic factors—specifically employment status, educational attainment, and household income—strongly affect the travel behavior of teens and young adults, but these factors strongly affect the travel of older adults as well.

Following this opening chapter, the second chapter of the report briefly reviews the research literature on teen and young adult travel. The third chapter discusses the methodology used to examine our four travel outcome measures. In chapter four, we discuss previous research on each of our factors of interest—(i) information and communications technology use, (ii) graduated driver’s licensing, and (iii) macro-economic effects on employment status and young adults living at home—and provide descriptive statistics on each from the NPTS/NHTS data. Chapters six through nine present the findings from our analyses of (1) personal miles traveled (PMT), (2) activity participation (number of daily trips), (3) trip purpose (4) commute mode, and (5) social trip mode. Finally, in the last chapter of the report, we summarize our findings and discuss the implications of these findings for both public policy and future research.