In the wake of devastating economic collapse, the United States was wounded and divided, plagued by angry extremists demanding the right to define who was an American. Then came Pearl Harbor and somehow, Americans banded together in a heroic war effort that inspired the enduring celebration of the Greatest Generation.

Following a brutally divisive presidential election ultimately decided by the Supreme Court, when the country seemed irredeemably split between red and blue in political and cultural conflict, the 9/11 terrorist attacks overnight generated a wave of patriotic consensus.

But if the experiences of the 1940s and early 2000s led many Americans to believe that major crises could heal or at least paper over severe divisions, this year’s trifecta of troubles — a deadly pandemic, an unprecedented insurrection at the Capitol and a chaotic close to the war in Afghanistan — has many wondering if the country has lost its capacity to come together in a moment of crisis.

Bitter discord is not a new response to the frightening spread of a lethal infection: In the 1918 flu pandemic, the country was sharply divided and trust in experts and authorities seemed to collapse.

This year, Sen. Tim Kaine, the Virginia Democrat, and Sen. Tommy Tuberville, an Alabama Republican, have voted on opposite sides 84 percent of the time, but they share troubling doubts about whether the country could meet a crisis with concerted action.

A constituent from Loudoun County recalled for Kaine recently that after the attacks of Sept. 11, 2001, Democrats and Republicans came together on the Capitol steps, sang an impromptu “God Bless America” and prayed for the country — scenes not likely to be repeated today, he said. Instead, this year’s crises have led to images of discord — prominent Republicans minimizing the Jan. 6 assault on the Capitol, or the spate of physical attacks on flight attendants enforcing mask rules on airplanes to curb the coronavirus.

“The ability of the leaders of the country to pull together is dramatically eroded,” the constituent told Kaine, and the senator says “that made a huge impression on me. There is certainly reason for worry.”

When coaching a football team, as Tuberville did for decades before turning to politics last year, “you’ve got different ideas on your staff, but at the end of the day, you come together for the good of the team,” the senator said. “We don’t have that now. I hear so many people say, ‘It’s my way or the highway.’ ”

The reasons why Americans might not be inclined to join forces in a crisis are themselves examples of the country’s divide — and of its history as a nation born in disunity. On the left, many blame Republicans for fomenting suspicion of others, whether they be foreigners, immigrants or minorities. On the right, many say Democrats have splintered the nation by emphasizing ethnic, racial and gender identities.

But there’s much agreement across the spectrum on how this pervasive disunity is getting locked in: The rise of social media and collapse of the country’s local news infrastructure have funneled many Americans into separate, often contradictory information worlds.

Americans are self-segregating residentially, moving to places where they live primarily among people with similar political and cultural outlooks.

Major life choices such as military service, college education, attendance at religious services and commuting practices often shape or cement people’s places on one side or the other of the American divide.

The barriers to joining hands against a common enemy may be most evident in election results, but the underlying antagonism extends far beyond partisan politics. It’s plain to see in measures of trust, confidence about the future, even in whom we’ll date or marry, with more than 6 in 10 Americans saying it would be difficult or impossible to get involved with someone who disagrees with them on abortion, gun rights or immigration, according to an American Enterprise Institute survey.

Mistrust of elites, experts, scientists, government and the news media has ballooned in recent years. After the 2000 election, when the Supreme Court ruled that George W. Bush had defeated Al Gore to win the presidency, Americans said by wide margins in a Gallup poll that the high court was the proper place to settle the disputed vote and that its decision did not diminish their confidence in the court. Two decades later, in the same poll, confidence in the high court has eroded.

Similarly, trust in national news organizations, especially among Republicans, has nosedived, falling from 70 percent of Republicans in 2016 to 35 percent this year, according to a Pew Research Center survey.

What this adds up to, according to experts on both the left and the right, is enough suspicion and antagonism to stir anxiety about whether Americans can still unite against a common threat.

“Will it take another attack on the United States to bring us together?” asked Robert E. Litan, an economist and fellow at the liberal Brookings Institution who worked in President Bill Clinton’s administration. “I’m depressed to give this answer: We just had an attack — covid — and it divided us even more deeply.”

If China were to try to take Taiwan by force, or if Russia mounted a military assault on Ukraine or the Balkans, Litan said, “maybe we’d be briefly united in outrage, but then the finger-pointing would start.”

After the 9/11 attacks, most Americans believed the nation had been badly traumatized but had also been jolted into a sense of common purpose and indeed had been changed for the better. But over time, that sentiment has flipped: In a Washington Post-ABC News poll this summer, a plurality of Americans said the terrorist attacks changed the country for the worse, leaving a legacy of discord and disunity. In the same poll, a majority of Americans said that after an initial burst of applause for health workers and support for short-term lockdowns, the coronavirus pandemic was tearing the country apart.

The depth of anger and malice in the air has persuaded Robert Jeffress, pastor of the 14,000-member First Baptist Church in Dallas, that this is the most polarized period in the nation’s history since the Civil War.

“I don’t see any great coming together being possible right now,” said Jeffress, who was one of President Donald Trump’s most prominent evangelical supporters. “And the evidence is the crisis we’re in now that has taken 650,000 lives.”

Even in his own church, where members tend to be conservative Republicans, the divisions are so deep that Jeffress, who is vaccinated against the coronavirus and strongly believes others should be, too, has decided he will not speak to his flock about vaccines, masks and the like.

“The vaccines are a gift from God, and we all have a responsibility to protect the people around us,” he said. “I disagree with Joe Biden on just about every issue, but I happen to believe he’s right about the mandates. We’ve got to stop automatically saying, ‘If the other side is for it, I’m against it.’

“But we’re not willing to divide our church over this. My calling is not to be the minister of vaccination, but to be a preacher of God’s word.”

Those who argue that the country is too splintered to confront crises point to the failure to stem the spread of the virus, including threats against school board members over mask and vaccine requirements, and the schadenfreude heard in near-celebratory comments about radio talk-show hosts, politicians and Internet influencers who trumpeted their mistrust of the vaccines before themselves dying of covid-19.

Just three years ago, Litan, the economist, argued that “America has held together through worse times.” Even as Trump seemed eager to pit one faction in the country against the other and as swift technological change transformed American life — from the nature of work to where people lived — Litan remained optimistic.

After all, people had found ways to come together even after the Civil War’s conflagration over race and slavery and after the generational and social conflict of the Vietnam War and the Watergate scandal.

Three years later, Litan has changed his mind. “I’m a lot more pessimistic now,” he said. In 1968, “people thought things were falling apart.” There were troops in the streets of American cities, riots, assassinations of revered leaders, bombings, violent confrontations on college campuses.

“But we didn’t have an insurrection at the Capitol, we didn’t have multiple versions of the truth, we didn’t have social media, and we didn’t have one party actively politicizing the counting of votes to destroy confidence in our elections,” he said. “Now, the trust in the election system ain’t there, and I don’t know how we get it back. We are in a state of cold civil war.”

But hold on: Was there ever really a time when Americans readily and easily found consensus? Paul Cantor, an English professor at the University of Virginia who has written extensively on how popular culture reflects the country’s character, looks across history and sees far more discord than harmony.

“This has always been a deeply fractious nation,” Cantor said. “The idea of a very contentious country is built into the Constitution — it’s what James Madison wanted from the start. The original question about this country was and remains, can you have a country without consensus? The whole idea behind America was that nobody has the truth,” so the founders created checks and balances to prevent any one force or faction from gaining control.

Americans have always been suspicious of leaders who preach compromise and consensus. From Westerns to World War II movies, from the counterculture of the ’60s to recent works presenting hackers and rogue entrepreneurs as heroes, pop culture has celebrated outsiders who do end runs around the elites and outsmart the experts — a theme Cantor sees being repeated in the backlash against Anthony S. Fauci, President Biden’s chief medical adviser.

It’s difficult to coalesce against a crisis when it’s not even clear anymore what constitutes a crisis, Cantor argues. In a time of 500 TV channels and infinite space on the Internet, media outlets worked ever harder to build audiences and “news channels began to present everything as a crisis,” he said. “The human ability to mobilize around a crisis is diminished when everything is a crisis.”

The unity, goodwill and social consensus that many say has leached out of American life was actually a rare phenomenon, widely associated with the 1950s, Cantor said. It was a time of three TV networks, an essentially all-White pop culture, and a narrowly defined sense of what it meant to be an American.

“At the time, people despised it,” he said. “They called it conformity.”

The following six decades brought battles for civil rights, legal protections for women and Blacks, a dramatic shift in sexual mores and family structures, and fairly constant social strife over abortion, same-sex marriage, affirmative action, immigration and gun control.

“We’re always falling apart in this country, and now we are in an era of centrifugal forces,” Cantor said.

Cable TV’s proliferation of channels for specialized interests and the advent of social media gave Americans the opportunity to follow their own narrow paths, paying ever less attention to the whole.

The splintered media landscape, the spread of misinformation on social platforms, and disinformation campaigns by the Russians and by domestic extremists have corralled many Americans into news silos consisting of one ideologically skewed version of reality. That has left many suspicious of those on the other side — “inundated with points of view that separate us,” said Jeffress, the pastor.

“People now have trouble distinguishing between truth and rumor,” and they end up angrily defending their own sheltered enclave of information, he said. “That’s true of Christians, too. We’re divided along political lines. We need to get back to what St. Augustine said: ‘In the essentials, unity. In nonessentials, liberty. In all things, charity.’ ”

In a more balkanized country, in which many people focus on their ideology, race, gender, ethnicity or sexuality as much as their identity as Americans, the idea of rallying to a shared patriotism has been politicized, said Kevin Gaines, a historian at the University of Virginia who focuses on the country’s struggles with racial integration.

“Since Ronald Reagan, Republicans have successfully redefined patriotism as military strength, family values and hard-working White Americans versus racial minorities who were on the dole,” he said. President Barack Obama tried to reclaim the idea of patriotism as a unifying force in a country that embraced all its citizens and viewed government as an essential part of the national identity, Gaines said, “but that didn’t gain traction,” and Obama’s efforts to bring factions together with moderate policies failed.

“He was constantly upended by Republican obstruction” that sought to suppress Black voting, the historian said. The country emerged from the Obama years with “an anti-democratic movement in response to the relative unity in Black America,” Gaines said.

Despite the country’s history of abiding conflict, especially over slavery, race and who gets to be full-fledged Americans, “there have always been moments of unity, often inspired by attacks from external enemies,” Gaines said. “We’ve always had anti-democratic elements, such as white supremacists and proto-fascists in the 1930s, but they fought alongside Black troops in World War II.

“Now, we have the need to rally against an internal threat, and we’re in completely new territory, with a level of polarization that overrides the sense of collective purpose.”

For Gaines, education is a key path toward regaining the ability to come together. “History offers us a lot of warnings about the grim future we are facing,” he said, “and that’s our opportunity to look the facts in the face and hopefully avoid that grim destiny.”

But across the divide, education can be an obstacle. Tuberville, who coached at Auburn, Texas Tech and Cincinnati before being elected to the Senate, says that by emphasizing the country’s history of racial strife, too many schools “are teaching us division, teaching people not to come together.”

Instead, the senator said, schools should focus on moral values and teaching young people how to defend themselves against disinformation and “understand that not everything you read is true.”

To Kaine, the way to rebuild common purpose is to demonstrate real progress to a skeptical electorate. In Virginia, even though the death penalty and Confederate statues were divisive, emotional issues within recent memory, “there’s been a dramatic change and real consensus,” Kaine said, as the state banned capital punishment and removed memorials to the likes of Confederate Gen. Robert E. Lee.

Although Virginia has become reliably Democratic in recent elections, a huge partisan gulf remains, so when Biden’s $1.9 trillion stimulus plan was passed this year, including Paycheck Protection Program loans for people who lost income because of the pandemic, it was unpopular in the state’s conservative counties.

But after the bill became law, Kaine visited the town of Damascus, near the Tennessee border, in a county where he won only 28 percent of the vote in his last election, and Biden won just 23 percent last year. There, at the Bank of Damascus, the marquee outside blasted good news: “PPP Loans Are Back!”

“That doesn’t solve the divisions,” Kaine said, “but getting results can help slowly create a different consensus. I am naive enough to believe that good policy is good politics. It’s still possible to win people over, and we still have the capacity to unify against an external threat.”