Changes in driving, population, motoring population and what their effect is on air

I am interested in driving statistics relative to population growth. With a growing population, how have the miles drivers drive and gallons of gasoline consumed changed over the years? The reason for the interest revolves around the impact the above has had on driving-produced emissions. If emissions from the motor vehicle sector are becoming less because there is less driving overall and motor vehicle fuel efficiency is improving, then this is obviously a good thing. However, if the number of miles ticked off rises, the gains in air quality improvement could be offset despite the better vehicle fuel economy.

So, how is America doing? I consider here three states where the amount of driving is considerable – California, Illinois and New York. Referenced are statistics from the Office of Highway Policy Information, Federal Highway Administration.


Looking at the period between 1980 and 2011, California population went from 23.668 million to 37.692 million. Meanwhile, the number of drivers escalated from 15.669 million in 1980 to 23.857 million in 2011. In 1980, of the total state population, the percent driving was 66.2 and whereas in 2011, the percent driving was 63.3. What this means is per total population, the number driving are fewer.

Furthermore, vehicle miles traveled (VMT) jumped from 156 billion in 1980 to 320.674 billion in 2011.

Meanwhile, the amount of gasoline consumed by vehicles in state in 2011 was 14.610 billion gallons, up from 10.745 billion gallons in 1980.

The next metric of importance to look at is fuel economy. In order to determine this requires the knowledge of how many cars were operating on California roadways and what the per-capita VMT was for the two selected years.

The per-capita VMT can be determined by dividing the VMT by the number of drivers. So, for 1980, per-capita California VMT was 9,956. For 2011, per-capita VMT in state was 13,441.5.

Therefore, motor vehicle fuel economy can be found by dividing total miles driven by fuel consumed. In 1980, the per-car average miles per gallon rating was 14.518 and for 2011, the per-car average mpg was 21.949.

And, last but not least, what this shows is that although automobile fuel economy has improved, both total and per-capita VMT have increased potentially zeroing out any gains made in air quality improvement which is basically a zero-sum game.

All things being equal, without further improvement in fuel economy and without an increase in the numbers of zero-polluting vehicles, there will be an increase overall in emissions coming from motor vehicles operating in California.


The 1980 Illinois population was 11.427 million. The population in 2011 was 12.869 million. Meanwhile, the number driving in the former year was 7 million while for the latter year that number was 8.374 million. For the former year the percent driving was 60.3 and for the latter year the percent driving was 65.07, a trend opposite that of California’s.

Additionally, VMT went from 65.086 billion to 103.234 billion for 1980 and 2011, respectively.

Fuel consumed by motor vehicles in Illinois: In 1980, the amount of motor vehicle fuel consumed was 4.493 billion gallons and for 2011 fuel consumed was 4.669 billion gallons.

Add to this that per-capita VMT was 12,328 in 2011 which was up from 9,298 in 1980.

As for vehicle fuel economy, improving in the Land of Lincoln as in the Golden State as well, in 1980 average vehicle fuel economy was 14.5 mpg and in 2011 the average car mpg rating was 22.1, essentially mirroring the mpg numbers of California cars.

New York

In the Empire State, from a 1980 population of 17.558 million this rose to 19.465 million in 2011. The numbers of New Yorkers driving went from 9.24 million in 1980 to 11.211 million in 2011. The percent of drivers relative to overall population in 1980 was 52.6 compared with a 2011 percentage of 57.6. So, basically, a little more than half the state population of New York drives.

Now, in taking a look at the VMT statistics, 77.62 billion miles and 127.726 billion miles were logged in 1980 and 2011, respectively.

Regarding fuel consumed, it was 5.36 billion gallons in 1980 and in 2011 it was 5.429 billion gallons.

Nineteen-eighty’s average vehicle per-capita VMT was 8,400 versus 2011’s 11,393 average per-capita VMT which trended similarly to both California and Illinois.

Where the rubber meets the road of course is in regard to fuel economy. In 1980, average vehicle mpg rating was 14.48 while in 2011 the average vehicle mpg rating was 23.53.

The takeaways

In all three cases, car fuel economy ratings were similar. California’s average per-capita VMT was highest with 13,441.5 while New York had the lowest with 11,393, each of which is above the national average which is south of 10,000.

Fuel economy ratings of automobiles has significantly improved which if an indication of things to come, this is good news. The greater the improvement, the better.

And for all three states, the numbers of those driving compared to the total populations is hovering at an average 62 percent. However, the percentage of those driving in both Illinois and New York is on the upswing, while the reverse is true in California. Population overall continues its upward ascent.

Emissions coming from the motor vehicle sector are what they are. But, with even better fuel economies and with even greater numbers driving zero-polluting cars and trucks, expect even greater gains down the road. The news is encouraging. However, should the volume of internal-combustion-engine-powered automobiles plying America’s roads significantly increase, offset could be the gains already made.

Something drivers may want to take into consideration regarding future vehicle purchases and leases.


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