In 1979 there were over 51,000 autombile related deaths in the United States. Since then we have made dramatic improvements to auto safety. The data clearly shows this.
Where did this improvement come from? If we track improvement in auto deaths and control for population, we can show the year to year improvement.
The large improvement zones are ’79-82, ’88-91, and we seem to be in the middle of a monster improvement since 2006.
I don’t have the answer yet for what is working, but here are some interesting dates.
Year the drinking age became universally 21: 1984
First mandatory seat belt law (NY): December, 1984
Passive restraints (Airbags or Automatic seat belts) required in all cars: 1989
I think there’s a time window between something like the 1989 airbag law and when a significant number of airbag equipped vehicles make an appearance on the road. I have no data on that yet, but the case for a delayed effect seems accurate. Another hypothesis isn’t drivers or cars, but improvements to roads and/or law enforcement. Most major highways around me have added reflectors, signs, and rumble strips to help prevent accidents. If you have any other hypotheses, post them in the comments.
Update: A lot of great comments, thanks! There are also a bunch over at the Hacker News thread. Many point to miles driven and automobile stability systems as good data to incorporate into the model. I also changed the years of “large improvement” which were off before. They now line up pretty well with recessions, but what is interesting is that we don’t give much back once the economy ramps up again. Maybe everyone buys a newer, safer car then
Update: Please read my follow up post on this. The answer is alcohol related accidents.