More People are Driving, But People Aren't Driving More

Last week, I wrote about this year's uptick in nationwide driving rates. In particular, I asked whether the regions that had begun to invest more in expanding transportation options rather than ever-expanding highways might be bucking the broader trend. Especially paired with fuel prices that have been steadily increasing for weeks, people have more of an incentive than ever to moderate their miles.

The Brookings Institution's Rob Puentes and Adie Tomar, writing over at The New Republic, looked at the data a different way. As their graph above shows, driving rates have only gone up in absolute terms. If you take into consideration population increases, the amount that each person drives annually has stayed about the same -- which is actually about the same amount that it was back in 2000. (The graph also shows a pretty clear connection with aforementioned fuel prices...) To connect back to my original question about transportation options, data from the American Public Transportation Association show that, during a similar period between 2000 and 2008, per capita use of public transit rose about 7 percent.

What is most interesting is that this new flattening of per capita driving rates follows decades of per capita increases. Between 1977 and 2001, driving in the United States grew by 151 percent - about 3 times faster than population. The average length of car trips, the number of car trips per capita, and the proportion of drivers traveling alone all increased as well. All of which contributed to the steep rise in global warming pollution from transportation in the U.S.

Eric Morris at the Freakonomics website isn't terribly satisfied with the idea that changing infrastructure policies can have a major impact on driving so quickly, even combined with fuel prices and broader economic factors. He did link back to Lee Schipper and Adam Millard-Ball's provocative paper suggesting that there might be a level of "peak travel" associated with personal income levels.

Whatever the truth behind them, the trends don't lie. This is good news for advocates of transportation efficiency - investing in cleaner transportation options such as streetcars, bus rapid transit, car-sharing, and transportation management technology. It means that our baseline for transportation emissions won't rise as steeply as we thought, and if we move forward with proposals to reform U.S. transportation policies, it will allow us to further reduce emissions and oil consumption from U.S. transportation.