WASHINGTON — U.S. traffic deaths soared by 18.4% in the first six months of 2021 to the highest number in the period since 2006, the Transportation Department said Thursday.

Traffic deaths have risen dramatically after coronavirus lockdowns ended in 2020 as more drivers engaged in unsafe behavior like speeding, regulators say. NHTSA on Thursday estimated 20,160 people died car crashes in the first six months of 2021 in the United States, up 3,140 over the same period in 2020.