Explaining the rise in traffic deaths in the last two years may be difficult to explain:

Cars may be safer than ever, but 37,461 people died on American roads that year, a 5.6 percent hike over 2015. While fatalities have dramatically declined in recent decades, this is the second straight year the number has risen. It’s too early to say why, exactly, this is happening. Researchers will need much more time with the data to figure that out. But here’s a hypothesis: It’s the economy, (crash) dummy.

“People drive more in a good economy,” says Chuck Farmer, who oversees research at the Insurance Institute for Highway Safety. “They drive to different places and for different reasons. There’s a difference between going out to a party in the middle of the night in an unfamiliar area and driving to work—that nighttime driving to a party is more risky.”…

Researchers have long known that driving deaths rise and dive with the economy and income growth. People with jobs have more reason to be on the road than the unemployed. But this increase can’t be pinned on the fact of more driving, the stats indicate. Even adjusted for miles traveled, fatalities have ticked up by 2.6 percent over 2015. You can still blame the economy, because people aren’t just driving more. They’re driving differently. Better economic condition give them the flexibility to drive for social reasons. There might be more bar visits (and drinking) and trips along unfamiliar roads (with extra time spent looking at a map on a phone).

The DOT numbers seem to confirm that drivers involved in traffic deaths were doing different things behind the wheel last year. The feds say the number people who died while not wearing seat belts climbed 4.6 percent, and that drunk driving fatalities rose 1.7 percent. Contrary to what you might expect, the numbers show distracted driving deaths dropped slightly, but experts caution against putting too much faith in such info. The numbers are based on police reports. They’re reflections of what cops are seeing at crash sites, but also of what’s in the zeitgeist at the time. It could be that first responders weren’t, for example, looking out for distracted driving last year because it wasn’t in the news as often.

Official statistics do not provide all the information we might want. In this case, the figure of interest to many will simply be the total number of deaths. Is an increase over two years enough to prompt rapid action? If so, I would imagine the regulatory structures regarding driverless cars might attract some attention. Or, do car deaths continue to be the costs we pay for having lifestyles built around driving?