Susannah Locke:

Yes, it is possible for Americans to drive less. And we have been. Although the general trend since 1971 has been more and more miles on the road, we’ve been traveling about 7 percent fewer miles per person since 2005. And fewer miles means fewer crashes.
 Why? For a variety of reasons. Higher oil prices have pushed people to drive less. Fewer people were driving during the recession. The country is aging, and older people tend to drive less on average. And young people seem to have a cultural aversion to driving, for reasons laid out here.