We are dying less

According to an article in the Strib Road toll is lowest since 1945, the number of traffic fatalities was down to 475 people in Minnesota for the year 2006 (from 655 people in 2003 and 1060 in 1968). This is a significant and non-random improvement in traffic safety, and notable given the continuing increase in total travel (indicating safety per trip or per mile has improved even more).
How much of the improvement is due to better vehicles, better weather, better roads, better drivers, better law enforcement, or better emergency response is an important question, as it may help direct resources toward the most productive areas additional improvements. I suspect a large part of the recent trend is emergency response, especially with the advent and widespread adoption of cell phones in the last decade leading to faster notification and response, as well as better medical treatment in hospitals for injured persons.