Jennifer Smith doesn’t like the term “accident.” It implies too much chance and too little culpability.

A “crash” killed her mother in 2008, she insists, when her car was broadsided by another vehicle while on her way to pick up cat food. The other driver, a 20-year-old college student, ran a red light while talking on his mobile phone, a distraction that he immediately admitted and cited as the catalyst of the fatal event.

“He was remorseful,” Smith, now 43, said. “He never changed his story.”

Yet in federal records, the death isn’t attributed to distraction or mobile-phone use. It’s just another line item on the grim annual toll taken by the National Highway Transportation Safety Administration – one of 37,262 that year. Three months later, Smith quit her job as a Realtor and formed Stopdistractions.org, a nonprofit lobbying and support group. Her intent was to make the loss of her mother an anomaly.

To that end, she has been wildly unsuccessful. Nine years later, the problem of death-by-distraction has gotten much worse.

Over the past two years, after decades of declining deaths on the road, U.S. traffic fatalities surged by 14.4 percent. In 2016 alone, more than 100 people died every day in or near vehicles in America, the first time the country has passed that grim toll in a decade. Regulators, meanwhile, still have no good idea why crash-related deaths are spiking.

There are however three big clues. One is the substantial increase in smartphone use by U.S. drivers. From 2014 to 2016, the share of Americans who owned an iPhone, Android phone, or something comparable rose from 75 percent to 81 percent.

The second is the changing way in which Americans use their phones while they drive. These days, we’re pretty much done talking. Texting, Twitter, Facebook, and Instagram are the order of the day-all activities that require far more attention than simply holding a gadget to your ear or responding to a disembodied voice. By 2015, almost 70 percent of Americans were using their phones to share photos and follow news events via social media. In just two additional years, that figure has jumped to 80 percent.

Finally, the increase in fatalities has been largely among bicyclists, motorcyclists, and pedestrians – all of whom are easier to miss from the driver’s seat than, say, a 4,000-pound SUV – especially if you’re glancing up from your phone rather than concentrating on the road. Last year, 5,987 pedestrians were killed by cars in the U.S., almost 1,100 more than in 2014.

Safety regulators and law enforcement officials certainly understand the danger of taking or making a phone call while operating a piece of heavy machinery. They still, however, have no idea just how dangerous it is, because the data just isn’t easily obtained. And as mobile phone traffic continues to shift away from simple voice calls and texts to encrypted social networks, officials increasingly have less of a clue than ever before.