“E pluribus unum” — out of many, one — is one of America’s traditional mottos. And you might think it would be reflected in reality. We aren’t, after all, just united politically. We share a common language; the unrestricted movement of goods, services and people is guaranteed by the Constitution. Shouldn’t this lead to convergence in the way we live and think?

In fact, however, the past few decades have been marked by growing divergence among regions along several dimensions, all closely correlated. In particular, the political divide is also, increasingly, an economic divide. As The Times’s Tom Edsall put it in a recent article, “red and blue voters live in different economies.”

What Edsall didn’t point out is that red and blue voters don’t just live differently, they also die differently.

About the living part: Democratic-leaning areas used to look similar to Republican-leaning areas in terms of productivity, income and education. But they have been rapidly diverging, with blue areas getting more productive, richer and better educated. In the close presidential election of 2000, counties that supported Al Gore over George W. Bush accounted for only a little over half the nation’s economic output. In the close election of 2016, counties that supported Hillary Clinton accounted for 64 percent of output, almost twice the share of Trump country.

The thing is, the red-blue divide isn’t just about money. It’s also, increasingly, a matter of life and death.

Back in the Bush years I used to encounter people who insisted that the United States had the world’s longest life expectancy. They hadn’t looked at the data, they just assumed that America was No. 1 on everything. Even then it wasn’t true: U.S. life expectancy has been below that of other advanced countries for a long time.

The death gap has, however, widened considerably in recent years as a result of increased mortality among working-age Americans. This rise in mortality has, in turn, been largely a result of rising “deaths of despair”: drug overdoses, suicides and alcohol. And the rise in these deaths has led to declining overall life expectancy for the past few years.

What I haven’t seen emphasized is the divergence in life expectancy within the United States and its close correlation with political orientation. True, a recent Times article on the phenomenon noted that life expectancy in coastal metropolitan areas is still rising about as fast as life expectancy in other advanced countries. But the regional divide goes deeper than that.

A 2018 article in The Journal of the American Medical Association looked at changes in health and life expectancy in U.S. states between 1990 and 2016. The divergence among states is striking. And as I said, it’s closely correlated with political orientation.

I looked at states that voted for Donald Trump versus states that voted for Clinton in 2016, and calculated average life expectancy weighted by their 2016 population. In 1990, today’s red and blue states had almost the same life expectancy. Since then, however, life expectancy in Clinton states has risen more or less in line with other advanced countries, compared with almost no gain in Trump country. At this point, blue-state residents can expect to live more than four years longer than their red-state counterparts.

Is this all about deaths of despair in the eastern heartland? No. Consider our four most populous states. In 1990, Texas and Florida had higher life expectancy than New York and almost matched California; today, they’re far behind.

What explains the divergence? Public policy certainly plays some role, especially in recent years, as blue states expanded Medicaid and drastically reduced the number of uninsured, while most red states didn’t. The growing gap in educational levels has also surely played a role: Better-educated people tend to be healthier than the less educated.

Beyond that, there has been a striking divergence in behavior and lifestyle that must be affecting mortality. For example, the prevalence of obesity has soared all across America since 1990, but obesity rates are significantly higher in red states.

One thing that’s clear, however, is that the facts are utterly inconsistent with the conservative diagnosis of what ails America.

Conservative figures like William Barr, the attorney general, look at rising mortality in America and attribute it to the collapse of traditional values — a collapse they attribute, in turn, to the evil machinations of “militant secularists.” The secularist assault on traditional values, Barr claims, lies behind “soaring suicide rates,” rising violence and “a deadly drug epidemic.”

But European nations, which are far more secularist than we are, haven’t seen a comparable rise in deaths of despair and an American-style decline in life expectancy. And even within America these evils are concentrated in states that voted for Trump, and have largely bypassed the more secular blue states.

So something bad is definitely happening to American society. But the conservative diagnosis of that problem is wrong — dead wrong.

WASHINGTON — Life expectancy increased for the first time in four years in 2018, the federal government said Thursday, raising hopes that a benchmark of the nation’s health may finally be stabilizing after a rare and troubling decline that was driven by a surge in drug overdoses.

Life expectancy is the most basic measure of the health of a society, and declines in developed countries are extremely unusual. But the United States experienced one from 2015 to 2017 as the opioid epidemic took its toll, worrying demographers who had not seen an outright decline since 1993, during the AIDS epidemic. An uptick in what have become known as “deaths of despair” — younger people dying from overdoses, suicide and alcoholism — has drawn considerable attention from politicians and policymakers.

The 2018 data, released in a report on Thursday, confirmed the first decline in drug deaths in 28 years, an important improvement after decades of rises.

The increase in life expectancy it helped produce was small — just over a month — and demographers cautioned that it was too early to tell if the country had turned the corner with opioid overdoses, which have claimed nearly 500,000 lives since the late 1990s.

“It’s good news, but we don’t know yet if it’s the beginning of a new trend,” said Elizabeth Arias, a demographer at the National Center for Health Statistics, which released the report.

Still, the rise was welcome news in states like Ohio, which in 2018 had the biggest decline in overdose deaths in the country.

“It’s literally like coming out of a fog,” said Andrew Wright, 34, who has been drug-free since August 2018, when he entered treatment at the Counseling Center in Portsmouth, Ohio. Medicaid, the government insurance program, covered his care. “It’s like I’m 22 and I’ve finally made it out of my parents’ house, embracing life for the first time. I’m learning how to live.”

The last time life expectancy in the United States flatlined for several years was in the 1960s, when the mass habit of smoking, particularly among men, began showing up in the mortality statistics, said Dr. Samuel Preston, a demographer at the University of Pennsylvania. But from 1968 to 2010, life expectancy went up by an average of about two years a decade, he said, a substantially slower rate than in European countries, but twice as fast as the increase in 2018.

Life expectancy at birth rose to 78.7 years in 2018 from 78.6 the previous year. It peaked at 78.9 in 2014, but has fallen or been flat since then.

Dr. Preston pointed out that the small rise in 2018 merely put the country back where it was in 2010, amounting to nearly a decade of stagnation, rare for a wealthy country.

Improvements in cancer mortality rates represented the single largest share of the life expectancy gain in 2018, about 30 percent. Next came the decline in so-called unintentional injuries, which include deaths from car accidents and drug overdoses. That category accounted for about 25 percent of the gain, a change that was driven almost entirely by a decline in drug deaths, Dr. Arias said.

Recent widespread efforts to expand access to opioid addiction medications, clean needles and naloxone — the drug used to revive people overdosing on opioids — may be having an impact.

“Good things are happening that hadn’t before, like sheriffs, hospitals and others who now use naloxone telling me, ‘We saved a life,’” said Shane Hudson, president and chief executive of CKF Addiction Treatment in Salina, Kan. His clinic is treating 117 people with medication for opioid addiction, up from 35 two years ago.

Deaths from overdoses dropped by 4.1 percent in 2018, to 67,367 from 70,237 in 2017. The decrease was largely driven by a dip in deaths from prescription opioid painkillers, which set off the opioid epidemic in the late 1990s before heroin and, later, fentanyl moved in. Provisional data suggests those deaths continued to fall in 2019, likely in part because of restrictions on prescribing.

But the death rate from fentanyl rose by 10 percent in 2018, and early data suggests it kept rising last year, though not as sharply as before. There were more overdose deaths in 2018 than in any year on record except 2017, and nearly 70 percent involved opioids.

A separate federal report, also released Thursday, found that the rate of drug overdose deaths dropped in 14 states in 2018, climbed in five and stayed about the same in the rest. The five states whose rates climbed were California, Delaware, Missouri, New Jersey and South Carolina. Ohio saw the biggest drop, to 3,980 overdose deaths in 2018 from 5,111 in 2017.

With the fentanyl death rate still climbing, along with deaths involving cocaine and psychostimulants like methamphetamine, it is not clear whether the overall drop will be sustained.

Mr. Wright, of Delaware, Ohio, developed an opioid addiction when he was 23, starting with prescription pills and moving to heroin. He said he spent years, on and off, sleeping in his car, under bridges and on his parents’ screened porch in the winter under a table so his father wouldn’t see him.

But he has now stayed off drugs for the longest period in his adult life, he said, a fact he attributes to his treatment program together with a change in the attitudes of the people in his town. A small grooming products company, Doc Spartan, hired him to make beard oil and grenade-shaped soap. Someone sold him a cheap car. Others helped him start sorting out his life — getting driver’s license, dealing with his unpaid bills and getting treatment for hepatitis C.

“I literally feel like I’m a soldier in this war, and I really like it,” said Mr. Wright, who now works as a trainer at PSKC, a CrossFit gym, and at a halfway house.

Another bright spot in Thursday’s data was cancer mortality. The overall cancer death rate dropped by 2.2 percent in 2018, a substantial decline.

Rebecca Siegel, the scientific director of surveillance research at the American Cancer Society in Atlanta, said the new data appeared to extend gains from 2017, when the overall cancer mortality rate drop was the largest since record-keeping beganaround 1930.

These improvements were driven largely by a decline in the mortality rate for lung cancer, the leading cause of cancer death. Continued drops in the country’s smoking rate and advances in treatment, such as more precise tumor classification, better surgical techniques, and improved drug therapies, contributed to the progress, Ms. Siegel said.

Despite this good news, the United States lags far behind most European countries in life expectancy. John Haaga, a demographer who retired from the National Institute on Aging in December, said that when he first started his job in 2004, life expectancy in the United States was about equal to that of Portugal, a much poorer country. Over his career, Portugal gained four years while the United States gained only one. He pointed out that life expectancy was longer in Costa Rica, Cuba and Slovenia.

The increase in life expectancy might have been greater if not for rising mortality due to influenza and pneumonia — the death rate grew by 4.2 percent — as well as suicide and nutritional deficiencies. But while there has been increased concern about suicide as a public health crisis, the growth in reported cases — to 48,344 in 2018 from 47,173 in 2017 — was relatively small. The suicide rate grew by 1.4 percent overall, with a larger rise for men than women.

Jill Harkavy-Friedman, a vice president at the American Foundation for Suicide Prevention, said the nation needed to invest far more in research to understand emerging patterns.

“I’ve been a researcher in this area for 30 years and I can tell youthe conversation and the funding has definitely changed,” she said, “but it’s still nowhere near the level of funding for any other public health problem of this scope.”

A federal report last fall found that the suicide rate among adolescents was at its highest level in 20 years, although the total number of teenagers who died by suicide in 2017 was fewer than 2,500. Jane Pearson, chairwoman of the Suicide Research Consortium at the National Institute of Mental Health, said there was no definitive explanation as of yet for the climbing suicide rate.

“We are worried about adolescents in particular showing increases in depression and anxiety, and trying to understand what’s driving all of this,” she said. “We can’t measure a lot of things that we would like to.”

Deaths of despair

It’s hard to imagine a more alarming sign of a society’s well-being than an inability to keep its citizens alive. While some of the reasons are mysterious, others are fairly clear. American society has become far more unequal than it used to be, and the recent increases in mortality are concentrated among working-class Americans, especially those without a four-year college degree.

For many, daily life lacks the structure, status and meaning that it once had, as the Princeton University economists Anne Case and Angus Deaton have explained. Many people feel less of a connection to an employer, a labor union, a church or community groups. They are less likely to be married. They are more likely to endure chronic pain and to report being unhappy.

These trends have led to a surge of “deaths of despair” (a phrase that Case and Deaton coined), from drugs, alcohol and suicide. Other health problems, including diabetes and strokes, have also surged among the working class. Notably, the class gaps in life expectancy seem to be starker in the U.S. than in most other rich countries.

Covid, of course, has aggravated the country’s health inequalities. Working-class Americans were more likely to contract severe versions of Covid last year, for a mix of reasons. Many could not work from home. Others received lower-quality medical care after getting sick.

Since vaccines became widely available this year, working-class people have been less likely to get a shot. At first, vaccine access was playing a major role. Today, vaccine skepticism is the dominant explanation. (All of which suggests that Covid will continue to exacerbate health disparities beyond 2020; yesterday’s report on life expectancy did not include data for 2021.)

Race and sex

Covid has also caused sharp increases in racial inequality. As a Times article on the new report explains:

From 2019 to 2020, Hispanic people experienced the greatest drop in life expectancy — three years — and Black Americans saw a decrease of 2.9 years. White Americans experienced the smallest decline, of 1.2 years.

I exchanged emails with Case and Deaton yesterday, and they pointed out that racial patterns contain some nuances. Hispanic Americans live longer on average than non-Hispanic Americans, both Black and white — yet the impact of Covid was worst among Hispanics. “This is not simply a story of existing inequalities just getting worse,” Case and Deaton wrote.

The fact that many Hispanic people work in frontline jobs that exposed them to the virus surely plays a role. But Black workers also tend to hold these jobs. It’s unclear exactly why Covid has hit Hispanic communities somewhat harder than Black communities (and would be a worthy subject for academic research).

Covid has also killed more men than women, Case and Deaton pointed out, increasing the mortality gap between the sexes, after years in which it had mostly been shrinking. Life expectancy was 5.7 years longer for women last year, up from 5.1 years in 2019. The gap had fallen to a low of 4.8 years in the early 2010s.

The bottom line: Covid has both worsened and exposed a crisis in health inequality. But that crisis existed before Covid and will continue to exist when the pandemic is over.

The average life expectancy of Americans fell precipitously in 2020 and 2021, the sharpest two-year decline in nearly 100 years and a stark reminder of the toll exacted on the nation by the continuing coronavirus pandemic.

In 2021, the average American could expect to live until the age of 76, federal health researchers reported on Wednesday. The figure represents a loss of almost three years since 2019, when Americans could expect to live, on average, nearly 79 years.

The reduction has been particularly steep among Native Americans and Alaska Natives, the National Center for Health Statistics reported. Average life expectancy in those groups was shortened by four years in 2020 alone.

The cumulative decline since the pandemic started, more than six and a half years on average, has brought life expectancy to 65 among Native Americans and Alaska Natives — on par with the figure for all Americans in 1944.

In 2021, the shortening of life span was more pronounced among white Americans than among Black Americans, who saw greater reductions in the first year of the pandemic.

While the pandemic has driven most of the decline in life expectancy, a rise in accidental deaths and drug overdoses also contributed, as did deaths from heart disease, chronic liver disease and cirrhosis, the new report found.

Until now, experts have been accustomed to measuring life expectancy changes in increments of months, not years.

“Even small declines in life expectancy of a tenth or two-tenths of a year mean that on a population level, a lot more people are dying prematurely than they really should be,” said Robert Anderson, chief of mortality statistics at the N.C.H.S.

“This signals a huge impact on the population in terms of increased mortality,” he added.

Dr. Steven Woolf, director emeritus of the Center on Society and Health at Virginia Commonwealth University, characterized the diminution of life expectancy in the United States as “historic.”

While other high-income countries were also hard hit in 2020, the first year of the pandemic, most had begun to recover by last year,he said.

“None of them experienced a continuing fall in life expectancy like the U.S. did, and a good number of them saw life expectancy start inching back to normal,” Dr. Woolf said.

Those countries had more successful vaccination campaigns and populations that were more willing to take behavioral measures to prevent infections, such as wearing masks, he said, adding: “The U.S. is clearly an outlier.”

But the coronavirus was not solely to blame. Longstanding health problems — rooted in poverty, discrimination and poor access to health care — left Native Americans and Alaska Natives particularly vulnerable to the virus, said Dr. Ann Bullock, former director of diabetes treatment and prevention at the federal Indian Health Service agency and a member of the Minnesota Chippewa Tribe.

One in seven Native Americans and Alaska Natives has diabetes, the highest rate among racial or ethnic groups in the United States, and many struggle with obesity or excess weight. Both conditions make people more susceptible to severe Covid-19, and crowded multigenerational housing adds to the risk.

“There is no doubt Covid was a contributor to the increase in mortality during the last couple of years, but it didn’t start these problems — it made everything that much worse,” Dr. Bullock said.

Average life expectancy in these populations is now “lower than that of every country in the Americas except Haiti, which is astounding,” said Noreen Goldman, professor of demography and public affairs at the Princeton School of Public and International Affairs.

The continued plunge was all the more upsetting because it occurred after a successful vaccination campaign, she said, adding: “The Native American population did quite well in the vaccination efforts, and that made us feel that 2021 would not be as devastating as 2020.”

“That was wrong, and it’s pretty hard to swallow,” she added.

White Americans saw the second-largest decline in average life expectancy in 2021, a drop of one year, to 76.4 in 2021 from 77.4 in 2020. The decline was steeper than that among Black Americans, at seven-tenths of a year. That was followed by Hispanic Americans, whose life expectancy dropped only two-tenths of a year in 2021.

But both Black and Hispanic Americans were hit hard in 2020, the first year of the pandemic. Average life expectancy for Hispanic Americans fell by four years, to 77.9 from 81.9 in 2019. The figure for Black Americans declined almost as much, by more than three years to 71.5 years in 2020.

White Americans experienced the smallest decline during the first year of the pandemic, a drop of 1.4 years to 77.4 from 78.8. For white and Black Americans, life expectancy is now the lowest it has been since 1995, federal researchers said.

Asian Americans held the highest life expectancy among racial and ethnic groups included in the new analysis: 83.5 years, on average. The figure fell only slightly last year, from 83.6 in 2020.

It was the largest reduction in life expectancy in the United States over the course of a two-year period since the early 1920s, when life expectancy fell to 57.2 in 1923. That drop-off may have been related to high unemployment and suicide rates during an earlier recession, as well as a steep increase in mortality among nonwhite men and women.

Although the U.S. health care system is among the best in the world, Americans suffer from what experts have called “the U.S. health disadvantage,” an amalgam of influences that erode well-being, Dr. Woolf said.

These include a fragmented, profit-driven health care system; poor diet and a lack of physical activity; and pervasive risk factors such as smoking, widespread access to guns, poverty and pollution. The problems are compounded for marginalized groups by racism and segregation, he added.

The result is a high disease burden among Americans, and shorter life expectancy compared with that in comparable high-income nations over the last two decades, Dr. Woolf said.

Over a million Americans have died of Covid-19, and more died in 2021 than in 2020 despite the availability of vaccines. To date, only two-thirds of Americans are fully vaccinated, and only one-third have had a booster shot.

“The white population did worse in 2021 than communities of color, besides Native American and Alaska Natives,” Dr. Woolf said. “I think that’s very telling: It reflects the greater efforts by Black and Hispanics to get vaccinated, to wear masks and take other measures to protect themselves, and the greater tendency in white populations to push back on those behaviors.”

The longevity gap between men and women also grew by a couple of months in 2021. American women can now expect to live 79.1 years, almost six years longer than men, whose average life expectancy was 73.2 last year, according to the new data.

The longevity gap between the sexes has been increasing for more than a decade, after narrowing between 2000 and 2010 to about five years.