The good news: Over the last century, driving has become significantly safer, with the per-mile fatality rate dropping 90% between 1925 and 1997. The bad news: Motor-vehicle crashes continue to kill more than 33,000 people in the United States every year, making them the leading type of unintentional injury resulting in death. And fatalities rose in 2012, snapping a six-year streak of reduced deaths.

In reporting the increase, the National Highway Traffic Safety Administration stated that “it is too soon to speculate on the contributing factors,” but the potential role of distracted driving can’t be ignored. According to the Centers for Disease Control and Prevention (CDC), in 2012 driver distraction was a factor in 3,328 deaths, and an estimated 421,000 people were injured in crashes involving a distracted driver — a 9% increase from 2011. The Federal Highway Administration has estimated that distracted driving may be a factor in 10% of all crashes.

Many states have passed laws to reduce the number of deaths and injuries due to distracted driving. These laws may ban all use of handheld devices or specifically prohibit texting. Some laws target young drivers while others apply to all drivers. As of June 2014, 44 states and the District of Columbia had a law banning all drivers from texting and an additional 4 states prohibited young or new drivers from texting. No states currently ban the use of hand-free phones for all drivers, even though research has shown that they offer no improvement over hand-held devices.

A 2014 study published in the American Journal of Public Health, “Impact of Texting Laws on Motor Vehicular Fatalities in the United States,” looks at effectiveness of state texting bans on the prevention of fatal car accidents. The researchers — Alva O. Ferdinand, Nir Menachemi, Bisakha Sen, Justin L. Blackburn and Michael Morrisey, based at the University of Alabama at Birmingham and Leonard Nelson, based at Samford University — analyzed data from 48 states over the period 2000-10 (Alaska, Hawaii and the District of Columbia were not part of the study). The authors compared motor-vehicle fatality rates in states with texting bans and those without. For states with texting bans, they also took into account within-state fatality rate changes before and after these laws took effect.

The study’s findings include:

• During the study period, 31 of the 48 states had a law banning texting while driving. Of these, 24 states banned all drivers from texting and 7 banned only drivers below a certain age.
• Laws allowing police officers to pull over all drivers who are texting, regardless of age, resulted in a 5% reduction in the incidence of fatal accidents among individuals ages 15-21. This figure includes deaths of both drivers and non-drivers.
• States with laws that only allow police to pull over young drivers who are texting experienced an 11% drop in the incidence of motor vehicle fatalities for individuals ages 15-21.
• “Secondary” texting bans, which only allow police to issue texting citations while pulling a driver over for an unrelated offense, had no effect on fatality rates for any age group.
• No type of anti-texting law reduced fatality rates for individuals above age 21.
• Other factors that were associated with reduced motor-vehicle fatality rates included maximum speed limits not exceeding 70 miles per hour, administrative driver’s license revocation laws, graduated driver’s license laws, higher gasoline prices and higher state unemployment rates.

“Our analyses indicate that primarily enforced texting laws are associated with fatality reductions among younger individuals, both drivers and nondrivers,” the authors conclude. “Thus, our second main finding is that our results provide strong evidence that the primarily enforced texting laws seem to be reaching the intended subpopulations who are most at risk for texting while driving.”

Related research: A 2013 study, “U.S. Transportation Safety over Time: Cars, Planes, Trains, Walking, Cycling,” compares the relative safety of the primary modes of transportation in the United States. Among the findings: Highways are by far the most common place of transportation fatalities in the United States, 94%, and those in rural areas are particularly dangerous, with a fatality risk that is 2.7 times greater than that in urban areas. Males are three times more likely to die in a road accident than females, while people between the ages of 18 and 29 are at a 50% to 90% greater risk. Half of vehicle occupants who die in automobiles and light truck incidents (49%) were not wearing seat belts or using child safety seats, and alcohol played a role in approximately a third of all highway fatalities.

Keywords: cars, driving, safety, technology, cellphones, smartphones, texting, distracted driving