This reduction becomes more remarkable still when you consider how much more congested the roads are in 2015 compared with 1970. Back then, according to Federal Highway Administration data, there were 112 million licensed drivers in the United States; Today, there are 210 million. In other words, half-a-century ago, there was one fatality for every 1,866 licensed drivers, whereas now there is 1 death for every 6,400 of them.
Much of what’s changed is straightforward. Cracking down on drunk driving and a huge cultural shift toward prioritizing automotive safety have made real differences. Twenty years ago, just over half of people reported wearing seat belts. Today, national seat-belt use hovers around 87 percent. Seat belts and airbags save tens of thousands of lives per year, according to National Highway Traffic Safety Administration estimates. The development of other built-in technologies have made a difference, too. As more cars incorporate electronic stability control, which involves the computerized application of individual brakes to avoid fishtailing, an additional 10,000 lives a year could be saved, according to NHTSA estimates.
But there are other more nuanced factors that affect safety on the roads. Periods of economic recession, for example, have been repeatedly linked with big declines in traffic fatalities in the United States. This decline is especially pronounced among younger drivers, people between 16 and 24 years old—a demographic that might stay off the roads due to unemployment, then in turn reduce discretionary leisure travel, too. I mention this as a way of pointing out that some of the forces that affect road safety are more complicated than looking at how many people are buckling up or getting breathalyzed at any given time.
In the shift to a much safer driverless future, we face similar complexities. In 2015, driverless cars in the wild—like Google’s fleets on the roads in Mountain View, California, and in Austin, Texas—are still a novelty. But 20 years from now, driverless cars may be mainstream enough to be all over the country without actually being ubiquitous yet.
What will happen when driverless cars are increasingly taking to the roads, but human drivers are still operating, say, half of the cars out there? Some researchers believe safety will actually worsen during this time—at least for the people in cars driven by humans. This isn’t just because humans are worse drivers than computers—and, certainly, they are—but because humans will be forced to navigate a vehicular environment that lacks many of the cues we use now to get around.
“In many current situations, interacting drivers of conventional vehicles make eye contact and proceed according to the feedback received from other drivers,” wrote Michael Sivak and Brandon Schoettle, transportation researchers at the University of Michigan, in an essay for Time last month. “Such feedback would be absent in interactions with self-driving vehicles.”