The number of drug overdose deaths nationwide in 2024 fell to the lowest level since 2019, according to data released this week by the U.S. Centers for Disease Control and Prevention.

An estimated 80,391 died from overdose last year, a drop of 27% from the 110,037 deaths recorded in 2023. That’s the largest year-over-year decline in the 45 years the CDC has been tracking data.

Maine saw a slightly smaller decline of 20%, although the 2024 total was also the lowest annual amount since 2019. Last year’s drop also comes on the heels of a 16% decrease from 2022 to 2023.

Overdose deaths started to spike dramatically in Maine from 2013-2017, when users migrated from prescription opioid painkillers to heroin, which was less expensive and more accessible. The numbers dropped slightly for two years before the pandemic reversed what had been an encouraging trend. By that time, the powerful synthetic opioid fentanyl had taken root, driving up the number of deadly overdoses.

The biggest decline nationwide in 2024 was in deaths attributed to fentanyl, which is often trafficked into the U.S. from Mexico and China. From 2023 to 2024, the number of fentanyl-linked deaths dropped by 37%.

Only two states — Nevada and South Dakota — saw overdose deaths increase in 2024. Seven states, including nearby New Hampshire, experienced declines of 35% or more.

Policy experts say they are still researching what is driving the sharp reduction, but there are likely many factors, including increased availability of the overdose-reversing drug naloxone, expanded addiction treatment, shifts in how people use drugs and the impact of billions of dollars in opioid lawsuit settlement money.

Maine’s director of opioid response, Gordon Smith, said late last year that although things are trending in the right direction, the number of deaths remains historically high. And deaths aren’t always the best metric for success or failure.

“We could do everything right that we’re supposed to do, and our deaths could still go up,” he said.

Reporting from the Associated Press was used in this story