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Miles Driven Indicate Economic Contraction.

  • Written by Syndicated Publisher No Comments Comments
    August 23, 2011

    The Depart of Transportation’s Federal Highway Commission has released the latest report on Traffic Volume Trends, data through June. The lead observation is that travel on all roads and streets changed by -1.4% (-3.8 billion vehicle miles) for June 2011 as compared with June 2010 (PDF report).

    Here is a chart that illustrates this data series from its inception in 1970. I’m plotting the “Moving 12-Month Total on ALL Roads,” as the DOT terms it. See Figure 1 in the PDF report, which charts the data from 1986. My start date is 1971 because I’m encorporating all the available data from the DOT spreadsheets.

     

    The rolling 12-month miles driven contracted from its all-time high for 39 months during the stagflation of the late 1970s to early 1980s, a double-dip recession era. The current dip has lasted for 43 months and counting — a new record.

    The Population-Adjusted Reality

    Total Miles Driven, however, is one of those metrics that must be adjusted for population growth to provide the most revealing analysis, especially if we’re trying to understand the historical context. We can do a quick per-capita adjustment of the data using an appropriate population group as the divisor. I use the Bureau of Labor Statistics’ Civilian Noninstitutional Population Age 16 and Over (FRED seriesCNP16OV). The next chart incorporates that adjustment with the growth shown on the vertical axis as the percent change from 1971.

     

    Clearly, when we adjust for population growth, the Miles-Driven metric takes on a darker look. The nominal 39-month dip that began in May 1979 grows to 61 months, slightly more than five years. The trough was a 6% decline from the previous peak.

    The population-adjusted all-time high dates from June 2005. That’s 72 months — six years. And since the latest data is the lowest reading since the all-time high, the best we can hope for is that June “might” have been the trough. Our per-capita miles driven based on the age16-and-older population is about where we were as a nation in June 1997.

    From DOT: Monthly Miles Driven.

    Images: Flickr (licence attribution)

    About The Author

    My original dshort.com website was launched in February 2005 using a domain name based on my real name, Doug Short. I’m a formerly retired first wave boomer with a Ph.D. in English from Duke. Now my website has been acquired byAdvisor Perspectives, where I have been appointed the Vice President of Research.

    My first career was a faculty position at North Carolina State University, where I achieved the rank of Full Professor in 1983. During the early ’80s I got hooked on academic uses of microcomputers for research and instruction. In 1983, I co-directed the Sixth International Conference on Computers and the Humanities. An IBM executive who attended the conference made me a job offer I couldn’t refuse.

    Thus began my new career as a Higher Education Consultant for IBM — an ambassador for Information Technology to major universities around the country. After 12 years with Big Blue, I grew tired of the constant travel and left for a series of IT management positions in the Research Triangle area of North Carolina. I concluded my IT career managing the group responsible for email and research databases at GlaxoSmithKline until my retirement in 2006.

    Contrary to what many visitors assume based on my last name, I’m not a bearish short seller. It’s true that some of my content has been a bit pessimistic in recent years. But I believe this is a result of economic realities and not a personal bias. For the record, my efforts to educate others about bear markets date from November 2007, as this Motley Fool article attests.
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