WASHINGTON (Reuters) – U.S. traffic deaths soared after coronavirus lockdowns ended in 2020, hitting the highest yearly total since 2007 as more Americans engaged in unsafe behavior on U.S. roads, the National Highway Traffic Safety Administration (NHTSA) said Thursday.

For all of 2020, 38,680 people died on U.S. roads—up 7.2 percent or nearly 2,600 more than in 2019, even though Americans drove 13 percent fewer miles, preliminary data showed. The fatality rate hit 1.37 deaths per 100 million miles, the highest figure since 2006.

In the second half of 2020, the number of traffic deaths was up more than 13 percent.

NHTSA said the main behaviors that drove this increase included impaired driving, speeding and failure to wear seat belts.

Deaths involving motorists not wearing seat belts were up 15 percent, speeding related deaths jumped by 10 percent and fatal crashes involving alcohol rose 9 percent.

Michigan said traffic deaths in the state rose 10 percent in 2020 to the highest number since 2007, even as crashes fell 22 percent and injuries fell 22 percent.

“We intend to use all available tools to reverse these trends and reduce traffic fatalities and injuries,” said acting NHTSA Administrator Steven Cliff.

In an open letter to drivers in January, NHTSA said “fewer Americans drove but those who did took more risks and had more fatal crashes…It’s irresponsible and illegal to drive under the influence of drugs or alcohol, which not only puts your life at risk but the lives of others.”

Some experts said that as U.S. roads became less crowded, some motorists engaged in more unsafe behavior, including those who perceived police were less likely to issue tickets because of COVID-19. Data suggests a higher number of serious crashes last year involved drug or alcohol use than previously.

NHTSA said in October a study of early crash data after the pandemic lockdowns found that “drivers who remained on the roads engaged in more risky behavior, including speeding, failing to wear seat belts, and driving under the influence of drugs or alcohol.”