Drivers in California who are concerned about cellphone distraction may be wise to avoid the roads between 2 p.m. and 4 p.m. This is the time that drivers are most likely to be looking at smartphone screens instead of the road according to a recent study from Motus. Researchers from the Boston-based workforce management company say that American motorists drive more than 100 billion miles each year while distracted by electronic devices, and they expect the problem to get even worse in the coming years as smartphones become ever more ubiquitous.

The figures seem to support the theory that the recent alarming rise in road deaths is linked to smartphone use. Between 2013 and 2017, the number of car accidents in the United States increased by more than 700,000. During the same period, smartphone ownership among Americans grew from 55 to 77 percent.

The Motus distracted driving report also reveals that mobile workers are especially prone to using their cellphones while behind the wheel. The company’s vehicle management data indicates that mobile workers take 49 percent more trips than other drivers and each cover 1,200 miles every year while distracted. The ensuing accidents and the productivity lost because of them cost employers about $1,680 per year for each mobile worker according to the report.

Road safety experts have long believed that distraction is a far more serious problem than government accident figures suggest. This is because it is difficult to prove that a driver was talking to a passenger, adjusting their stereo or lighting a cigarette when they crashed. However, cellphone use leaves an electronic trail that can help law enforcement to determine the cause of a collision. These digital fingerprints may also provide valuable evidence to experienced personal injury attorneys pursuing car accident lawsuits on behalf of injured road users.