America's Driving Habits as of September 2020
The Department of Transportation's Federal Highway Commission has released the latest report on Traffic Volume Trends, data through August.
"Travel on all roads and streets changed by -8.6% (-23.4 billion vehicle miles) for September 2020 as compared with September 2019. Travel for the month is estimated to be 248.3 billion vehicle miles." The 12-month moving average was down 0.78% month-over-month and down 10.7% year-over-year. If we factor in population growth, the 12-month MA of the civilian population-adjusted data (age 16-and-over) was down 0.85% month-over-month and down 11.1% year-over-year.
Here's a detailed map of regional driving in September:
Here is a chart that illustrates this data series from its inception in 1971. It illustrates the "Moving 12-Month Total on ALL Roads," as the DOT terms it. As we can readily see, the Great Recession had a substantial impact on our driving habits, but habits bounced back over the next five or so years. The decline in driving was most likely related to the cost of gasoline during that time period (see fourth chart below). The COVID-19 pandemic has had a massive impact on driving as Americans are staying home for work, meals, and entertainment.
The rolling 12-month miles traveled contracted from its all-time high for 39 months during the stagflation of the late 1970s to early 1980s, a double-dip recession era. We are currently in the most rapid decline we've ever seen, though miles traveled are still not at all-time lows, even when adjusted for population (see below).
The Population-Adjusted Reality
Total Miles Traveled, however, is one of those metrics that should be adjusted for population growth to provide the most meaningful analysis, especially if we want to understand the historical context. We can do a quick adjustment of the data using an appropriate population group as the deflator. Let's use the Bureau of Labor Statistics' Civilian Noninstitutional Population Age 16 and Over (FRED series CNP16OV). 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-Traveled metric takes on a weaker 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 COVID-19 recession has put us at levels last seen in the early 1990s.