I see equal parts good news and bad news in this chart.

The good news is that vehicle travel, measured per person, has fallen pretty substantially in both Oregon and Washington since 2003.  In Oregon, the decline has been about 11 percent; in Washington, it’s been about 7 percent.  (Monthly data are from the Federal Highway Adminstration, by the way.)

Less driving has a bunch of benefits. It means that we don’t have to spend as much on cars, gas, and road infrastructure; that the risks and costs of car crashes fall; and that we reduce our per-person emissions of climate-warming gases.

To add to the good news:  the overall trends for the last six years suggest that Washington may be on track to meet the ambitious VMT reduction targets in the state’s 2008 green house gas statute.

Then there’s the bad news.  In both Washington and Oregon, vehicle travel has been on the rise since last fall.  The reasons for the uptick are welcome enough—modest signs of increased economic activity, coupled with gas prices that were well below their 2008 peaks.  Still, if the recent uptick in vehicle travel turns into a full-blown trend, all the benefits of reduced car dependence could evaporate.

But just as importantly, the graph above measures VMT per person — but the Northwest population has been growing, slowly but steadily.  In Washington, population growth has more or less negated all of the declines in per-person vehicle travel.  In Oregon, the overall vehicle travel trends are still down, but it’s a modest 4% decline—much smaller than the 11% decline you get when measure the trends per person.

I’ll take my good news where I can find it—and there really is some good news here.  But the real trick will be to create a transportation system that lets people get where they need to go, without a perpetual, unsustainable increase in vehicle travel.