The Department of Energy's Energy Information Administration EIA data on volume sales is over two months old when it released. The latest numbers, through mid-July, are now available. However, despite the lag, this report offers an interesting perspective on fascinating aspects of the US economy. Gasoline prices and increases in fuel efficiency are important factors, but there are also some significant demographic and cultural dynamics in this data series.

Because the sales data are highly volatile with some obvious seasonality, I've added a 12-month moving average MA to give a clearer indication of the long-term trends. The latest 12-month MA is 8.8% below the all-time high set in August 2005, a new interim low.

The next chart includes an overlay of real monthly retail gasoline prices, all grades and formulations, adjusted for inflation using the Consumer Price Index (the red line). I've shortened the timeline to start with EIA price series, which dates from August 1990. The retail prices are updated weekly, so the price series is the more current of the two.

As we would expect, the rapid rise in gasoline prices in 2008 was accompanied by a significant drop in sales volume. With the official end of the recession in June 2009, sales reversed direction … slightly. The 12-month MA hit an interim high in November 2010, and then resumed contraction. The moving average for the latest month is about 8.5% below the pre-recession level and 5.4% off the November 2010 interim high. For some historical context, the latest data point is a level first achieved in February 1998.

Some of the shrinkage in sales can be attributed to more fuel-efficient cars. But that presumably would be relatively small over shorter time frames and would be offset to some extent by population growth. For some specifics on fuel efficiency, see the Eco-Driving Index for new vehicles developed by the University of Michigan Transportation Research Institute. However, if we look at Edmunds.com for data on the top 10 best-selling vehicles, energy efficiency doesn't seem to be the key decision factor, to judge from the percentage of pickup trucks and of SUVs.

Average Daily Volume Sales Per Capita

The next chart adjusts the 12-month MA of sales volume for population growth based on the monthly data for Civilian Non-Institutional Population over age 16 from the Bureau of Labor Statistics, via the St. Louis FRED repository. What we see here is that gasoline sales on a per-capita basis are 8.6% lower than at the end of the Great Recession. The gallons-per-capita series includes the complete EIA data, but since I'm using the 12-month MA, the blue line starts in 1984. We see the double peak in March 1989 (the all-time high) and August 1990. The latest per-capita daily average is 22.0% below the 1989 high and a new interim low.

What does this analysis suggest about the state of the economy? From an official standpoint, the Great Recession ended 60 months before the most recent gasoline sales monthly data point. But if we want a simple confirmation that the economy is in recovery, gasoline sales continues to be the wrong place to look.

In addition to improvements in fuel efficiency, the decline in gasoline consumption is attributable in large part to some powerful secular changes in US demographics and cultural in general:

• We have an aging population leaving the workforce, which we clearly see in the sustained contraction in the employment-population ratio.
• There is growing trend toward a portable workplace and the ability to work from home (I'm a typical example).
• Social media have provided powerful alternatives to face-to-face interaction requiring transportation (Internet apps, games, the ubiquitous mobile phone for talk and texting).
• There has been a general trend in young adults to drive less (related to points two and three above). See this PDF report for details.
• The US is experiencing accelerating urban population growth, which reduces the per-capita dependence on gasoline.

For a striking example of an apparent "disconnect" between government transportation expenditures and demographics trends, see the WISPIRG commentary Driving Wisconsin's "Brain Drain".

As I've continued to observe, we are living in interesting times.