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The roads less traveled – vehicle miles traveled on the decline in St. Louis region

People in the region are not driving as much as in years past, that much is clear. Why they aren’t driving is not so clear, though if that question were posed on a multiple-choice test with a list of reasons for answers, the best choice would be “all of the above.”

Vehicle miles traveled, also known as VMT, is the metric most often used to gauge how much people are driving. For the city of St. Louis and the surrounding seven counties in Illinois and Missouri, VMT is down 4.4 percent from 2007 to 2011. For the same span nationally, VMT is down 2.8 percent, and it has declined yearly since 2004.  The knee-jerk analysis is that higher gasoline prices have kept people from driving, but the numbers don’t support that theory.

Jerry Blair, director of transportation for the East-West Gateway Council of Governments, points to a litany of reasons why VMT numbers are shrinking.

“Everyone knows it’s a combination of factors, but no one can say which factors predominate,” says Blair. “Economic downturn; stagnant household incomes that make the cost of transportation a more obvious outlay; aging of the population and the less than favorable view of the automobile among younger populations; automobile market saturation; increasing urban density; greater sensitivity to the time spent in cars; better jobs-housing balance; etcetera – take your pick.

“Research shows, however, that there is a very low correlation between VMT and gas prices, so price in and of itself has no significant impact,” Blair says.


Measuring VMT matters, in part because state governments are searching for new methods to fund the maintenance, repair and construction of roads. The current gasoline tax is problematic because it is a per-gallon tax that brings in increased revenue only when more gallons are sold. An increase in the cost of gasoline does not increase revenue from the gasoline tax. In addition, as cars become more fuel-efficient, drivers usually don’t need to buy as much gasoline.

Oregon has conducted VMT pilot studies that collect data on the number of miles a driver travels, and levies a fee at the pump when the motorist buys gasoline. Privacy concerns, and implementation costs, have led to some opposition of VMT-based plans. Virginia has moved to replace the gasoline tax with a tax on the wholesale fuel costs and an increase in the state sales tax. Other states are looking at various methods to overhaul transportation funding.

In the St. Louis region, Jefferson County had the steepest VMT decrease, dropping 8.2 percent from 2007 to 2011. Franklin County went down 7.7 percent. The smallest decline was St. Clair County, which decreased 2 percent. For the East-West Gateway region, the 4.4 percent VMT drop from 2007 through 2011 represented 2.9 million fewer vehicle miles traveled.

Whatever the reason for the driving decrease, the drift seems consistent.

“Hopefully it means people are finding more acceptable and less costly means of accessing the things they want,” says Blair. “Regardless of what happens with VMT, a VMT tax remains a better mechanism as both a user fee and a reliable source than the motor fuel tax.”

These articles explore different approaches to a VMT tax:

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