Newly released government data paint a sobering picture of safety on the nation's roads and highways.

The number of people who died in auto accidents reached 35,092 last year, according to newly released figures from the National Highway Traffic Safety Administration. That's a 7.2 percent increase over 2014. The last time there was such a large single-year increase was back in 1966, when Lyndon Johnson was president.

"Despite decades of safety improvements, far too many people are killed on our nation's roads every year," Transportation Secretary Anthony Foxx said in a press release announcing the new data. "Solving this problem will take teamwork, so we're issuing a call to action and asking researchers, safety experts, data scientists, and the public to analyze the fatality data and help find ways to prevent these tragedies."

Foxx's " call to action" to researchers also was announced in a separate statement.

Officials say the number of traffic fatalities was actually 25 percent higher a decade ago, when 42,708 people died on the road. But the number of deaths had been declining because of increased use of seat belts, fewer drunken drivers, and vehicle improvements such as air bags and electronic stability control.

Officials say the increase last year can be attributed to more people driving. Job growth and lower fuel prices factor in, and motorists are covering more ground.

"In 2015, vehicle miles traveled (VMT) increased 3.5 percent over 2014, the largest increase in nearly 25 years," according to NHTSA.

More people on the road mean more fatalities among pedestrians and cyclists. Motorcycle deaths were up more than 8 percent.

Officials cite three main causes for the increase in traffic fatalities:

  • Almost half of the deaths came when passengers were not wearing seat belts.
  • About 30 percent of fatalities involved a drunken driver or speeding.
  • Distracted driving was a factor in about 10 percent of auto deaths.
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