The progress comes as the Trump administration is proposing to cut funding for many programs believed to have contributed to the improvement.

Overdose deaths in the United States fell by nearly 30,000 last year, the government reported on Wednesday, the strongest sign yet that the country is making progress against one of its deadliest, most intractable public health crises.

The data, released by the Centers for Disease Control and Prevention, is the latest in a series of reports over the past year offering hints that the drug-related death toll that has gutted families and communities could be starting to ease.

Public health experts had been carefully watching the monthly updates, with skepticism at first, and then with growing hope. Wednesday’s report was the most encouraging yet. Deaths declined in all major categories of drug use, stimulants as well as opioids, dropping in every state but two. Nationwide, drug fatalities plunged nearly 27 percent.

“This is a decline that we’ve been waiting more than a decade for,” said Dr. Matthew Christiansen, a physician and former director of West Virginia’s drug control policy. “We’ve invested hundreds of billions of dollars into addiction.”

Addiction specialists said that changes in the illicit drug supply as well as greater access to drug treatment and the use of naloxone to reverse overdoses seemed to be playing a role, but whether the country could sustain that progress was an open question.

In announcing the new numbers, the C.D.C. praised President Trump, saying in a statement that since he “declared the opioid crisis a public health emergency in 2017” the government had added more resources to battle the drug problem.