Preliminary estimates from the National Safety Council indicate motor vehicle deaths were 8% higher in 2015 than they were in 2014 — the largest year-over-year percent increase in 50 years.

The National Safety Council estimated 38,300 people were killed and 4.4 million were seriously injured on U.S. roads in 2015. That means 2015 was likely was the deadliest driving year since 2008.

Over the past year at the state level, the National Safety Council estimates Oregon (27%), Georgia (22%), Florida (18%), and South Carolina (16%) all experienced increases in fatalities. But only 13 states showed improvement. Among them were New Mexico (-20%), Kansas (-7%) and New Jersey (-2%).

"These numbers are serving notice: Americans take their safety on the roadways for granted," said Deborah A.P. Hersman, president and CEO of the National Safety Council. "Driving a car is one of the riskiest activities any of us undertake in spite of decades of vehicle design improvements and traffic safety advancements. Engage your defensive driving skills and stay alert so we can reverse this trend in 2016." 

The estimate is subject to slight increases or decreases as data mature, NSC said. The organization has issued annual traffic fatality estimates since 1921. Over the past three years, preliminary estimates have fallen within 1% of final counts.

While many factors likely contributed to the fatality increase, NSC noted, a stronger economy and lower unemployment rates are probably at the core of the trend. Average gas prices were 28% lower in 2015 than in 2014 and are projected to continue dropping this year. As a result, driving was more affordable for many Americans. The U.S. Department of Transportation estimated a 3.5% increase in the number of miles driven in 2015 compared to 2014. 

To promote safe driving, the National Safety Council advises drivers to:

• Make sure every passenger buckles up on every trip

• Designate an alcohol and drug-free driver or arrange alternate transportation

• Get plenty of sleep and take regular breaks to avoid fatigue

• Never use a cell phone behind the wheel, even hands-free

• Stay engaged in teens' driving habits, since teens are three times as likely to crash as more experienced drivers.

Supplemental estimate information can be found here.