US highway fatalities spiked to 35,092 last year in the highest one-year increase in the tally since 1966, the Transportation Department said.

The National Highway Traffic Safety Administration is attributing the 7.2 percent increase in deaths on the highways to more driving due to job growth and lower gas prices as well as more driving by young people. Drunk drivers, speeding, and distraction from phones and other devices are contributing to the alarming increase.

“The data tell us that people die when they drive drunk, distracted, or drowsy, or if they are speeding or unbuckled,’’ NHTSA Administrator Mark Rosekind said in a statement Monday announcing the data. “While there have been enormous improvements in many of these areas, we need to find new solutions to end traffic fatalities.’’

The government has been sounding the alarm on rising highway fatalities. For decades the trend had been on a decline in both the raw number of highway deaths as well as the rate — the number of deaths per miles driving.

More bicyclist, pedestrian deaths

The report on 2015 fatalities also showed that more pedestrians and bicyclists died in roadway accidents than at any point in the last 20 years. Motorcyclist fatalities were up 8 percent.

Nearly half of the people killed on the highways weren’t wearing seat belts. Increased driving accounts for some, but not all, of the increase in fatalities: vehicle-miles-traveled was 3.5 percent higher in 2015 than the previous year. That was the highest one-year increase in 25 years.

Transportation Secretary Anthony Foxx issued a “call to action’’ to researchers, safety experts, and data scientists to analyze the statistics and find ways to save lives.

“Despite decades of safety improvements, far too many people are killed on our nation’s roads every year,’’ Foxx said. “Solving this problem will take teamwork.’’

Jeff Plungis in Washington at jplungis@bloomberg.net