Drug overdoses are driving up the death rate of young white adults in the United States to levels not seen since the end of the AIDS epidemic more than two decades ago — a turn of fortune that stands in sharp contrast to falling death rates for young blacks, a New York Times analysis of death certificates has found.

The rising death rates for those young white adults, ages 25 to 34, make them the first generation since the Vietnam War years of the mid-1960s to experience higher death rates in early adulthood than the generation that preceded it.

The Times analyzed nearly 60 million death certificates collected by the Centers for Disease Control and Prevention from 1990 to 2014. It found death rates for non-Hispanic whites either rising or flattening for all the adult age groups under 65 — a trend that was particularly pronounced in women — even as medical advances sharply reduce deaths from traditional killers like heart disease. Death rates for blacks and most Hispanic groups continued to fall.

The analysis shows that the rise in white mortality extends well beyond the 45- to 54-year-old age group documented by a pair of Princeton economists in a research paper that startled policy makers and politicians two months ago.

While the death rate among young whites rose for every age group over the five years before 2014, it rose faster by any measure for the less educated, by 23 percent for those without a high school education, compared with only 4 percent for those with a college degree or more.

The drug overdose numbers were stark. In 2014, the overdose death rate for whites ages 25 to 34 was five times its level in 1999, and the rate for 35- to 44-year-old whites tripled during that period. The numbers cover both illegal and prescription drugs.

“That is startling,” said Dr. Wilson Compton, the deputy director of the National Institute on Drug Abuse. “Those are tremendous increases.”

Rising rates of overdose deaths and suicide appear to have erased the benefits from advances in medical treatment for most age groups of whites. Death rates for drug overdoses and suicides “are running counter to those of chronic diseases,” like heart disease, said Ian Rockett, an epidemiologist at West Virginia University.

In fact, graphs of the drug overdose deaths look like those of deaths from a new infectious disease, said Jonathan Skinner, a Dartmouth economist. “It is like an infection model, diffusing out and catching more and more people,” he said.

Yet overdose deaths for young adult blacks have edged up only slightly. Over all, the death rate for blacks has been steadily falling, largely driven by a decline in deaths from AIDS. The result is that a once yawning gap between death rates for blacks and whites has shrunk by two-thirds.

“This is the smallest proportional and absolute gap in mortality between blacks and whites at these ages for more than a century,” Dr. Skinner said. If the past decade’s trends continue, even without any further progress in AIDS mortality, rates for blacks and whites will be equal in nine years, he said.

There is a reason that blacks appear to have been spared the worst of the narcotic epidemic, said Dr. Andrew Kolodny, a drug abuse expert. Studies have found that doctors are much more reluctant to prescribe painkillers to minority patients, worrying that they might sell them or become addicted.

“The answer is that racial stereotypes are protecting these patients from the addiction epidemic,” said Dr. Kolodny, a senior scientist at the Heller School for Social Policy and Management at Brandeis University and chief medical officer for Phoenix House Foundation, a national drug and alcohol treatment company.

Not many young people die of any cause. In 2014, there were about 29,000 deaths out of a population of about 25 million whites in the 25-to-34 age group. That number had steadily increased since 2004, rising by about 5,500 — about 24 percent — while the population of the group as a whole rose only 5 percent. In 2004, there were 2,888 deaths from overdoses in that group; in 2014, the number totaled 7,558.

Mortality rates, said Mark D. Hayward, a professor of sociology at the University of Texas at Austin, are one of the most sensitive measures of quality of life.

By that measure, said Anne Case, a Princeton economist, “there’s a real rumbling that bad things are coming down the pike.” Dr. Case made the original observation with her husband, the Nobel laureate Angus Deaton, in a published paper that showed death rates for middle-aged whites rising in contrast to those in every other rich country.

For young non-Hispanic whites, the death rate from accidental poisoning — which is mostly drug overdoses — rose to 30 per 100,000 from six over the years 1999 to 2014, and the suicide rate rose to 19.5 per 100,000 from 15, the Times analysis found.

For non-Hispanic whites ages 35 to 44, the accidental poisoning rate rose to 29.9 from 9.6 in that period. And for non-Hispanic whites ages 45 to 54 — the group studied by Dr. Case and Dr. Deaton — the poisoning rate rose to 29.9 per 100,000 from 6.7 and the suicide rate rose to 26 per 100,000 from 16, the Times analysis found

But deaths from the traditional killers for which treatment has greatly improved over the past decade — heart disease, H.I.V. and cancer — went down.

Maline Hairup died of a heroin overdose on Aug. 24, 2014. She was 38 and a Mormon, engaged to be married in the Salt Lake City Temple, near her home. Her religion taught her to spurn addictive substances — no alcohol, no caffeine. But that night, after years of taking prescription narcotics for chronic pain complicated by mental illness, she tried heroin, her sister Mindy Vincent said. Ms. Vincent believes it was the only time her sister used that drug.

Researchers are struggling to come up with an answer to the question of why whites in particular are doing so poorly. No one has a clear answer, but researchers repeatedly speculate that the nation is seeing a cohort of whites who are isolated and left out of the economy and society and who have gotten ready access to cheap heroin and to prescription narcotic drugs.

“There are large numbers of people who never get established in the economy, who live outside family relationships and are on the edge of poverty,” Dr. Hayward said. Many end up taking prescription narcotics, he added.

“Poverty and stress, for example, are risk factors for misuse of prescription narcotics,” Dr. Hayward said.