– After declining for most of the past decade, traffic deaths spiked 8 percent in the first half of this year, prompting a call from the nation’s highway safety chief to find ways to reduce the human errors that cause most fatalities.

The estimate released Tuesday by the National Highway Traffic Safety Administration came just as millions of Americans prepare to hit the road for the Thanksgiving holiday. AAA predicted that 42 million people will drive 50 miles or more over the weekend.

Officials released a final number of fatal crashes for 2014, which showed a decline of 0.1 percent. This year, lower gas prices and an improving economy are prompting people to travel more.

NHTSA Administrator Mark Rosekind said that not all of the increase could be attributed to people driving more miles. He suspects that texting and other distractions were part of the cause, as well as drunken, drugged and drowsy driving, and increased driving by teenagers.

“These numbers are a wake-up call,” Rosekind said.

The NHTSA said its research shows that human decisions cause 94 percent of all crashes. The agency plans to hold five meetings around the country early next year to get input on how to cut traffic deaths.

Rosekind said 2014 statistics showed that distracted driving caused about 10 percent of the 32,675 traffic deaths that year.

For 2014, the rate of fatalities fell to a record low of 1.07 deaths per million vehicle miles traveled. But 2015 estimates showed the death rate rising over 4 percent.

Last year was the safest on record for people inside vehicles, with 21,022 deaths.