—Apparently there have been some safety improvements in cars that can account for some of this.—
Like texting? It’s the reason I stopped bicycle commuting and gave up motorcycling.
I do think the price of gas has something to do with it, but that speaks to the economy. And the drop actually started just as we were getting wind that a bubble was crashing. I start the significant decline in 2007.
One figure I noticed when I was looking all this up is that about 9.4% of accidents are ascribed to "distracted driving". Of course maybe the real figure is a little higher. I agree that texting must be a significant portion of this. So the fatality figures would be even better if it weren't for the explosion in texting in the last five years. On the other hand, many states are now outlawing cell phone use while driving, so talking on the phone may have declined a little.
I do think the price of gas has something to do with it, but that speaks to the economy. And the drop actually started just as we were getting wind that a bubble was crashing. I start the significant decline in 2007.
It's not clear what the economy has to do with the drop in the number of fatalities per billion miles (don't want to dig this up again but it's with the fatality figures on Wikipedia). Maybe people are are driving slower to save gas, or they're not in a hurry to get anywhere and they're getting more sleep because they don't have jobs.
I don't know how plausible this is but some articles I saw claimed that there were some adjustments to SUVs that make them hit smaller cars lower down and this has resulted in fewer deaths.