In Anchorage, affluent families set off on ski trips and other lengthy vacations, with the assumption that their children can keep up with schoolwork online.

In a working-class pocket of Michigan, school administrators have tried almost everything, including pajama day, to boost student attendance.

And across the country, students with heightened anxiety are opting to stay home rather than face the classroom.

In the four years since the pandemic closed schools, U.S. education has struggled to recover on a number of fronts, from learning loss, to enrollment, to student behavior.

But perhaps no issue has been as stubborn and pervasive as a sharp increase in student absenteeism, a problem that cuts across demographics and has continued long after schools reopened.

Nationally, an estimated 26 percent of public school students were considered chronically absent last school year, up from 15 percent before the pandemic, according to the most recent data, from 40 states and Washington, D.C., compiled by the conservative-leaning American Enterprise Institute. Chronic absence is typically defined as missing at least 10 percent of the school year, or about 18 days, for any reason.

The increases have occurred in districts big and small, and across income and race. For districts in wealthier areas, chronic absenteeism rates have about doubled, to 19 percent in the 2022-23 school year from 10 percent before the pandemic, a New York Times analysis of the data found.

Poor communities, which started with elevated rates of student absenteeism, are facing an even bigger crisis: Around 32 percent of students in the poorest districts were chronically absent in the 2022-23 school year, up from 19 percent before the pandemic.

Even districts that reopened quickly during the pandemic, in fall 2020, have seen vast increases.

“The problem got worse for everybody in the same proportional way,” said Nat Malkus, a senior fellow at the American Enterprise Institute, who collected and studied the data.

The trends suggest that something fundamental has shifted in American childhood and the culture of school, in ways that may be long lasting. What was once a deeply ingrained habit — wake up, catch the bus, report to class — is now something far more tenuous.

“Our relationship with school became optional,” said Katie Rosanbalm, a psychologist and associate research professor with the Center for Child and Family Policy at Duke University.

The habit of daily attendance — and many families’ trust — was severed when schools shuttered in spring 2020. Even after schools reopened, things hardly snapped back to normal. Districts offered remote options, required Covid-19 quarantines and relaxed policies around attendance and grading.

Today, student absenteeism is a leading factor hindering the nation’s recovery from pandemic learning losses, educational experts say. Students can’t learn if they aren’t in school. And a rotating cast of absent classmates can negatively affect the achievement of even students who do show up, because teachers must slow down and adjust their approach to keep everyone on track.

“If we don’t address the absenteeism, then all is naught,” said Adam Clark, the superintendent of Mt. Diablo Unified, a socioeconomically and racially diverse district of 29,000 students in Northern California, where he said absenteeism has “exploded” to about 25 percent of students. That’s up from 12 percent before the pandemic.

Why Students Are Missing School

Schools everywhere are scrambling to improve attendance, but the new calculus among families is complex and multifaceted.

At South Anchorage High School in Anchorage, where students are largely white and middle-to-upper income, some families now go on ski trips during the school year, or take advantage of off-peak travel deals to vacation for two weeks in Hawaii, said Sara Miller, a counselor at the school.

For a smaller number of students at the school who qualify for free or reduced-price lunch, the reasons are different, and more intractable. They often have to stay home to care for younger siblings, Ms. Miller said. On days they miss the bus, their parents are busy working or do not have a car to take them to school.

And because teachers are still expected to post class work online, often nothing more than a skeleton version of an assignment, families incorrectly think students are keeping up, Ms. Miller said.

Across the country, students are staying home when sick, not only with Covid-19, but also with more routine colds and viruses.

And more students are struggling with their mental health, one reason for increased absenteeism in Mason, Ohio, an affluent suburb of Cincinnati, said Tracey Carson, a district spokeswoman. Because many parents can work remotely, their children can also stay home.

For Ashley Cooper, 31, of San Marcos, Texas, the pandemic fractured her trust in an education system that she said left her daughter to learn online, with little support, and then expected her to perform on grade level upon her return. Her daughter, who fell behind in math, has struggled with anxiety ever since, she said.

“There have been days where she’s been absolutely in tears — ‘Can’t do it. Mom, I don’t want to go,’” said Ms. Cooper, who has worked with the nonprofit Communities in Schools to improve her children’s school attendance. But she added, “as a mom, I feel like it’s OK to have a mental health day, to say, ‘I hear you and I listen. You are important.’”

Experts say missing school is both a symptom of pandemic-related challenges, and also a cause. Students who are behind academically may not want to attend, but being absent sets them further back. Anxious students may avoid school, but hiding out can fuel their anxiety.

And schools have also seen a rise in discipline problems since the pandemic, an issue intertwined with absenteeism.

Dr. Rosanbalm, the Duke psychologist, said both absenteeism and behavioral outbursts are examples of the human stress response, now playing out en masse in schools: fight (verbal or physical aggression) or flight (absenteeism).

Quintin Shepherd, the superintendent in Victoria, Texas, first put his focus on student behavior, which he described as a “fire in the kitchen” after schools reopened in August 2020.

The district, which serves a mostly low-income and Hispanic student body of around 13,000, found success with a one-on-one coaching program that teaches coping strategies to the most disruptive students. In some cases, students went from having 20 classroom outbursts per year to fewer than five, Dr. Shepherd said.

But chronic absenteeism is yet to be conquered. About 30 percent of students are chronically absent this year, roughly double the rate before the pandemic.

Dr. Shepherd, who originally hoped student absenteeism would improve naturally with time, has begun to think that it is, in fact, at the root of many issues.

“If kids are not here, they are not forming relationships,” he said. “If they are not forming relationships, we should expect there will be behavior and discipline issues. If they are not here, they will not be academically learning and they will struggle. If they struggle with their coursework, you can expect violent behaviors.”

Teacher absences have also increased since the pandemic, and student absences mean less certainty about which friends and classmates will be there. That can lead to more absenteeism, said Michael A. Gottfried, a professor at the University of Pennsylvania Graduate School of Education. His research has found that when 10 percent of a student’s classmates are absent on a given day, that student is more likely to be absent the following day.

Is This the New Normal?

In many ways, the challenge facing schools is one felt more broadly in American society: Have the cultural shifts from the pandemic become permanent?

In the work force, U.S. employees are still working from home at a rate that has remained largely unchanged since late 2022. Companies have managed to “put the genie back in the bottle” to some extent by requiring a return to office a few days a week, said Nicholas Bloom, an economist at Stanford University who studies remote work. But hybrid office culture, he said, appears here to stay.

Some wonder whether it is time for schools to be more pragmatic.

Lakisha Young, the chief executive of the Oakland REACH, a parent advocacy group that works with low-income families in California, suggested a rigorous online option that students could use in emergencies, such as when a student misses the bus or has to care for a family member. “The goal should be, how do I ensure this kid is educated?” she said.

In the corporate world, companies have found some success appealing to a sense of social responsibility, where colleagues rely on each other to show up on the agreed-upon days.

A similar dynamic may be at play in schools, where experts say strong relationships are critical for attendance.

There is a sense of: “If I don’t show up, would people even miss the fact that I’m not there?” said Charlene M. Russell-Tucker, the commissioner of education in Connecticut.

In her state, a home visit program has yielded positive results, in part by working with families to address the specific reasons a student is missing school, but also by establishing a relationship with a caring adult. Other efforts — such as sending text messages or postcards to parents informing them of the number of accumulated absences — can also be effective.

In Ypsilanti, Mich., outside of Ann Arbor, a home visit helped Regina Murff, 44, feel less alone when she was struggling to get her children to school each morning.

After working at a nursing home during the pandemic, and later losing her sister to Covid-19, she said, there were days she found it difficult to get out of bed. Ms. Murff was also more willing to keep her children home when they were sick, for fear of accidentally spreading the virus.

But after a visit from her school district, and starting therapy herself, she has settled into a new routine. She helps her sons, 6 and 12, set out their outfits at night and she wakes up at 6 a.m. to ensure they get on the bus. If they are sick, she said, she knows to call the absence into school. “I’ve done a huge turnaround in my life,” she said.

But bringing about meaningful change for large numbers of students remains slow, difficult work.

The Ypsilanti school district has tried a bit of everything, said the superintendent, Alena Zachery-Ross. In addition to door knocks, officials are looking for ways to make school more appealing for the district’s 3,800 students, including more than 80 percent who qualify for free or reduced-price lunch. They held themed dress-up days — ’70s day, pajama day — and gave away warm clothes after noticing a dip in attendance during winter months.

“We wondered, is it because you don’t have a coat, you don’t have boots?” said Dr. Zachery-Ross.

Still, absenteeism overall remains higher than it was before the pandemic. “We haven’t seen an answer,” she said.