The Washington Post’s Wonkblog examines the trend of (especially younger) Americans driving cars less and posits some possible explanations.
I’m going to go out on a limb here and say that maybe it’s because driving is a tedious, expensive, and dangerous way to get around and you don’t get any exercise in the process. That’s leaving out all the external costs of digging up, transporting, and protecting the infrastructure needed for the fuel, of course. Duh. The real question in my mind is why it’s mostly just younger people who have figured this out.
Edit: did not realize it was Earth day… serendipity?