Will 2013 Continue The 7-Year Downward Trend In American Driving?

by Justin Horner, via NRDC’s Switchboard

Predictions and prognostications are the stuff of the New Year — and why should driving trends be any different? Will 2013 see a continuation of what has now been a nearly 90 month drop in population-adjusted Vehicle Miles Travelled (VMT)?

The safe answer, of course, is “well, we just don’t know” (or, “we just don’t know until Nate Silver takes the questions on”). In fact, the most recent data from the Federal Highway Administration’s Traffic Volume Trends Report (October 2012) shows an uptick in total VMT of about 0.6% over October 2011, with small increases in every region of the country, save the Hurricane Sandy-impacted Northeast.

Yet, it is unlikely that many of the broader factors that have led to VMT declines stark enough to give birth to the notion of “peak car” will be changing in any significant way in 2013. In November of last year, the International Transport Forum of the Organization for Economic Cooperation and Development held a round-table on Long-Run Trends in Travel Demand. The panelists focused on just these demographic, behavioral and long-run economic factors, the trends that have the greatest impact on driving demand in the coming years.


True transpo geeks will want to read the reports for themselves, but I’ll outline some of the most interesting tidbits here. First, some of what we would call “good news:”

  • Total US driving hit its peak in 2007. Since then, average annual VMT growth has been -0.5%, while average annual population growth has been 0.8%. Per capita VMT in August 2012 was about the same as it was in 2004;
  • Obviously, certain age groups drive far less than others: kids can’t drive, working adults with families drive the most, and some seniors shouldn’t be driving at all (if you ask me). In the coming years, then, as Boomers retire, they will drive less, and as Millennials enter their prime family and employment years, they’ll drive more. Yet, at least in the early years of the 21st Century, we’re seeing that every age cohort drove fewer miles per capita in 2008 than they did in 2001;
  • Younger Americans (aged 16 to 34) have made even more significant changes in the way they travel. Between 2001 and 2009, they cut their per capita VMT by 24%, took 16% more walk trips, 24% more bike trips, and travelled 40% more on public transit;
  • The number of licensed drivers in America is barely growing: Every age group under 50 has a smaller percentage of its population licensed in 2010 than in 1983. For the first time in American history, women with licenses outnumber men. Women do drive less, drive more slowly and more safely (as if you needed me to tell you that).

Among the explanations for these changing driving patterns?

  • You can’t drive without a car, so, not surprisingly, vehicle ownership has been a prime driver of VMT growth. Yet vehicle ownership is unlikely to grow as “there is near saturation of vehicle availability for the able-bodied adult population.
  • The post-1950 VMT surge was accompanied by historically unique workplace trends and income growth. A growing number of women workers needed to drive to get to work, and family incomes grew steadily, particularly from low to middle income levels. Neither of these trends is likely to continue in America going forward: women are already fully present in the workforce, and as incomes climb over middle income levels, they have been shown to instigate less VMT (and even correlate with VMT decline);
  • Housing market preferences and development trends will likely continue attracting Americans to more compact neighborhoods, cutting the length of trips and increasing opportunities to walk, bike and use transit. Reinvestment in our traditional urban areas will also continue. Central city growth is, indeed, outstripping regional averages in many areas.
  • “Marchetti’s Constant and the concept of personal travel budgets both present the reasonable idea that people will, or are really even able to, travel for only a certain amount of time per day. Marchetti says it’s an hour, regardless of your travel speed. Americans may have found that they’ve reached their own personal limit and are sick of driving, choosing less driving or alternatives if they have the option;
  • Technology, mobile phones, the internet…all have been quite logically connected to decreasing the need to drive, be it to work, shopping or a friend’s house. Unfortunately, there is as yet little empirical evidence establishing just what this impact can be. While the impacts of telecommuting are relatively well explored, we don’t know whether 10,000 new smartphones or laptops means, say, 100,000 fewer trips. Yet one thing is for sure: mobile technology is not going away. And many point to American young people’s “love affair with tech” as a reason they are choosing to drive less.

Long-term forecasting can be an inexact, even embarassing, affair, so I’ll avoid saying too much with too much confidence. What I’ll do instead is present the three hypotheses laid out by the Roundtable. For our distinguished panel, recent declines in driving are indicative of one of three trends:

  1. The Interrupted Growth Hypothesis: VMT cuts are temporary and increases will resume once the economy picks up (although we know more VMT is not a required, or inevitable, part economic growth);
  2. The Saturation Hypothesis: car ownership and personal travel budgets have hit their limit, so no more growth is likely;
  3. The Peak Car Hypothesis: VMT has hit its peak, and history will now see a VMT decline of undetermined length.

That’s right, folks. According to the experts, in the future VMT will either go up, go down, or stay the same.

I vote for “go down.”

Justin Horner is a policy analyst with the Natural Resources Defense Council. This piece was originally published at NRDC’s Switchboard and was reprinted with permission.