Coast to coast, major U.S. cities are seeing measurable drops in drug overdose deaths. Public health officials welcome the news despite an inability to fully explain the decrease.

After years of rising, the tide may finally be turning on deadly drug overdoses in America.

Drug overdose deaths fell 12.7% in the 12 months ending in May, according to preliminary data released Wednesday by the Centers for Disease Control and Prevention.

“This is the largest recorded reduction in overdose deaths,” White House officials said in a statement. “And the sixth consecutive month of reported decreases in predicted 12-month total numbers of drug overdose deaths.”

It’s also the first time since early 2021 that the number of estimated drug overdose deaths for a 12-month period fell below 100,000, to 98,820.

It’s categorically good news. It’s also a bit puzzling to the public health experts who have been working for years to stop the upward trajectory of opioid deaths, driven primarily by fentanyl.