When the school year began, Gettysburg College looked well-positioned to weather the tumult of the coronavirus pandemic and Arizona State University seemed vulnerable.

The private liberal arts college in Pennsylvania planned meticulously for the arrival of more than 2,200 students to its small-town campus in August, pledging to test them all for the novel coronavirus and do its utmost to safeguard public health while teaching as much as possible in person.

The public university in Arizona confronted the steep challenge of squelching infection threats on multiple campuses in the Phoenix area as it delivered a mix of face-to-face and online instruction to 74,000 students. What’s more, the virus surged across Arizona during the summer and made the state one of the nation’s most worrisome hot spots.

Yet Gettysburg’s opening crumbled, while Arizona State’s held up.

The college sent more than half its students home this month after infections were found to be spreading at an alarming rate. The university, meanwhile, kept its teaching and housing plans intact while it conducted tens of thousands of coronavirus tests on students and employees since Aug. 1. Arizona State reported 355 active cases among students as of last week, and just 96 of those lived in campus housing.

Arizona State President Michael M. Crow is cautiously optimistic about the fall term. But he knows the virus isn’t going to vanish any time soon.

“We’re operating under the assumption that covid is a permanent partner to the human ecosystem that we have to manage for the foreseeable future,” Crow said. “And we’re operating under that very, very daunting notion because it affects so many things that we do.”

The reopening of colleges amid a deadly pandemic has brought upheaval and uncertainty to campuses from coast to coast, with a staggering academic and emotional toll for students. But the chaos is not uniform.

Variations in testing protocols, campus locations and student housing patterns from school to school can play a huge role in success or failure. So do school culture, state politics and luck. Pauses and delays of in-person teaching can shape the outcome. Geography is critical: The pandemic waxes in some regions as it wanes in others.

A degree of stability, perhaps tenuous, has taken hold at many schools that brought students to campus. It is a remarkable turn after the spring crisis that forced students nationwide to evacuate and professors to pivot practically overnight from classrooms to remote instruction. Leaders of these schools say they are gaining confidence they can keep campuses on track with research, teaching and learning. Students are settling into the strangeness.

Sarah O’Brien, 21, is one of 1,800 undergraduates who came to Worcester, Mass., for the fall term at the private Clark University. She and her peers are tested every three days with nasal swabs, and so far there have been no outbreaks. People wear masks everywhere on campus, she said. In one of her classes, half of the students are seated in person on a given day and half are connected online. The next time, the groups switch. Taking turns helps maintain adequate physical distance.

“Some of my professors will joke that class is the safest place to be,” O’Brien said. It’s far from optimal, but it beats the alternative. “I think I’d go crazy if I was at home,” said the senior from Milford, Conn.

Extraordinarily difficult calls

Across America, though, many are still at home or living with friends away from campus and attending class remotely.

As of early September, 34 percent of 1,442 four-year colleges and universities tracked by researchers at Davidson College were teaching fully or primarily in person. Another 37 percent were teaching fully or primarily online. Most others took a combined approach known as “hybrid” learning. The researchers also found that public community colleges were more likely than four-year schools to be operating online.

For higher education leaders, these are extraordinarily difficult calls. They face competing and overlapping pressures from governors, governing boards, faculty, alumni, neighbors, parents and students.

Every day they are checking caseloads on campus and surrounding communities and wondering whether they have enough funding to operate, enough hospital beds nearby to handle any surge in cases, and enough dorm or hotel rooms to isolate those who are infected and quarantine those who might be. Parties at fraternity and sorority houses and other venues pose constant threats. Layered onto all that is the national debate over the wisdom of playing college football.

“I have had many agonizing conversations” with school leaders about the pandemic, said Peter McPherson, president of the Association of Public and Land-grant Universities. “This has been one of the toughest sets of decisions that presidents have made in their careers.”

Richard Ekman, president of the Council of Independent Colleges, sees a pattern that reflects regional differences over the need for pandemic restrictions. Schools in the South and Midwest, he said, tend to be opening more fully in person than those in the Northeast and on the West Coast. “It pretty much mirrors what you’re seeing in the politics of the country,” he said.

There is consensus on one point: Coronavirus testing helps. Frequent testing helps even more.

“Schools that are doing it every couple of days are staying on top of it,” said Gerri Taylor, co-chair of the American College Health Association’s covid-19 task force. Methods are evolving. Some schools are using less-invasive techniques than the testing that relies on long nasopharyngeal swabs. Some also are checking dorm wastewater for the virus.

McDaniel College, in Westminster, Md., tested 1,150 students when they moved onto campus, and it tests about 300 a week who are randomly selected. There have been a handful of cases at the private college. McDaniel President Roger Casey credits student commitment to public health but acknowledges: “Obviously, part of this is luck.”

Creating a bubble

Some small schools rely more on control of their campuses.

At Cheyney University of Pennsylvania, the country’s oldest historically Black college or university, 624 students live on or near the campus outside Philadelphia. The public school is not administering its own coronavirus tests.

Students who show symptoms are referred to an outside testing facility. Cheyney President Aaron A. Walton said there have been no reports of virus cases among students during the semester that began Aug. 10. Faculty have sought wide-scale testing, but the school has focused instead on enforcing the use of masks and physical distance between students. It also has established a campus perimeter.

“We’ve actually created a bubble with one way in and one way out,” Walton said. Food deliveries and Uber drivers enter only at the front gate. Campus visitors must complete health screenings, and students must pass temperature checkpoints in residence halls. Guests aren’t allowed inside dorms. Curfews are 11 p.m. on weeknights and midnight on weekends for students who leave campus.

“We have a fairly strict code of conduct,” Walton said.

In North Carolina, the private Duke University so far has dodged the viral surges that slammed two nearby public institutions in the state’s Research Triangle. The University of North Carolina at Chapel Hill and North Carolina State University were forced last month to send students home.

Through Sept. 11, nearly 30,000 tests of Duke students had turned up 40 positive cases. All but seven of those had been cleared by that date.

One lesson from Duke: Density matters. While Duke tested students more aggressively than UNC-Chapel Hill and North Carolina State, it also brought fewer to campus. Only freshmen, sophomores and a few others moved into dorms — 3,000 in all. Everyone has a single room, and traffic is much reduced in bathrooms and hallways.

Those who live nearby in Durham are only allowed on campus when they have a class. They can’t go to the dining halls, dorms or other places students would normally gather.

Duke officials are acutely aware that conditions could change at any moment. “Our mantra has been like a tournament: Survive and advance,” said Duke spokesman Michael Schoenfeld, who knows exactly how many days are left in the semester. “We want to get there. But we also want to get to Thursday.”

Fraternities and sororities are popular at Duke, but in contrast to counterparts elsewhere, they don’t have separate houses. That means there is more supervision. As a private university with a substantial endowment, Duke also has the funding to do what it wants.

Pressure on public universities

Public universities often face taller hurdles. They get significant pressure from politicians and students to reopen, but with less funding than prestigious private schools and less control over sprawling campuses and the many bars and restaurants that cater to them. Flagship universities in Alabama and Wisconsin have each reported more than 2,300 positive tests among students.

Campus culture matters.

“Testing alone obviously is not enough,” said Joshua M. Sharfstein, vice dean for public health practice and community engagement at Johns Hopkins Bloomberg School of Public Health. “Testing tells you where the virus is, but it doesn’t slow the virus down if people are not doing what they need to do to protect themselves or others.”

Educators have stressed personal responsibility in these huge schools, discouraging parties and promoting masks. Success can be elusive.

“We’re in a dance,” said West Virginia University President E. Gordon Gee. His 26,000-student university returned partially in person in August under a plan he likened to “a fox trot.” Then infections spiked, he said, “so we started dancing the waltz.” On Sept. 9, the university halted most face-to-face teaching of undergraduates for 2½ weeks to contain the outbreak. “Now we’re dancing the rumba,” Gee said. But the president himself recently misstepped. On Sept. 13, someone uploaded onto Twitter a photo of Gee shopping in a local pharmacy without wearing a mask. Gee subsequently apologized.

At the University of Tennessee, which has about 29,000 students, there were 600 active cases on the flagship campus in Knoxville within three weeks of its Aug. 19 start. More than 2,100 students were reported in quarantine or isolation in early September.

On Sept. 8, Tennessee Chancellor Donde Plowman said case counts were “going up way too fast” and expressed frustration with fraternities holding off-campus parties “crammed with lots of people in close quarters.” Some Greek life organizations were suspended for violating public health rules. To stem infections, the university switched campus dining to carryout, barred visitors from dorms and closed the fitness center. As of Saturday, the active case count had ebbed to about 340.

Instructors scrambled to adapt. Idil Issak, a graduate teaching assistant in anthropology, began the semester with an in-person course that met twice a week. But after six of her students were forced to isolate, Issak added online instruction to ensure no one would be left out.

Issak said students should not bear the brunt of blame for spikes in cases. The situation, she said, is Tennessee’s responsibility. “If they’re really being honest with themselves,” Issak said, university officials know “it’s their fault. They’re just wanting to make money off these kids.”

Some universities have opened in phases, buying time to guard against outbreaks. The University of Virginia, with 25,000 students, began undergraduate courses online in August. But many undergrads moved onto campus this month in Charlottesville, and in-person teaching launched after Labor Day. The 40,000-student University of Maryland at College Park took a similar path as a small share of classes met in person starting last Monday.

The delay helped U-Md. expand testing and gave faculty more time to prepare. “It certainly made me feel more secure about going back. It was less stressful for me,” said Sarah Ann Oates, a journalism professor who returned to the classroom. “In the end, it did make me feel safer.”

Geography matters

Geography helps the University of Vermont, in a state where the virus appears to be largely contained. More than 10,000 students descended last month on its Burlington campus. They have been tested frequently. Of nearly 33,000 tests administered as of last week, the university reported 19 positive cases. The university has worked hard to enforce public health rules. But Vermont President Suresh Garimella said responsibility for keeping the community safe should not be placed entirely on the students.

“Student behavior is important, but I didn’t want to set them up for failure,” Garimella said. Testing, he said, “is the basis of a sound strategy.”

The virus can wreak havoc even when schools put sharp limits on face-to-face teaching. California State University at Chico, which has about 16,000 students in Northern California, brought 750 into campus housing when the semester started in August. About 8 percent of its courses were offered in person, echoing the pattern elsewhere in the state.

Within days of opening, the university knew it had a problem. Several resident assistants, key to the operation of campus housing, were discovered to be infected with the virus or exposed to it. There was also a surge in campus-connected infections. And Butte County, which encompasses Chico, warned that more cases were appearing among young adults.

University President Gayle Hutchinson said she had no choice but to shift to all-online teaching and ask most dorm students to leave. “Probably one of the toughest decisions I’ve ever had to make,” Hutchinson said. “On paper, it should have worked. But in real life, with how this disease spreads, it wasn’t so.”

'Hindsight is 20/20'

Gettysburg College felt secure about the plan it dubbed “Better Together.” The liberal arts school, founded decades before the Civil War battle that the town is forever identified with, had expanded student housing, consulted with public health experts and arranged for viral testing.

Starting on Aug. 10, students showed up in staggered sequence at a gymnasium, checked in, underwent a throat-swab test and collected room keys. Then they quarantined until receiving results. Only a handful were positive for the virus.

But a second round of testing yielded more troubling data: 33 positives as of Aug. 29. The Gettysburgian student news outlet reported that a fraternity faced disciplinary action after hosting a social gathering without masks and distancing.

On Aug. 30, Gettysburg President Bob Iuliano pleaded with students to follow public health rules. “We are at an inflection point,” he said in an online town hall, “that requires all of us to take stock of how committed we are to staying together in our residential mode.” The college imposed an “all-student quarantine” on Sept. 1. But it was not enough. On Sept. 4, Iuliano announced the college would “de-densify” — sending 1,300 students home.

Up to 900 remain on campus — freshmen, transfers and certain others — and the new case count has dropped into the single digits.

Anna Cincotta, 21, a senior from Princeton, N.J., said she and other students got the move-out order in a mass email at 4:11 p.m. that Friday. She had less than two days to clear out. “All of us are reeling from being sent home,” she said.

What are the lessons from Gettysburg? Were there too many careless parties? Was the school overconfident? Or was it just bad luck? “That’s the question on everyone’s mind,” Cincotta said. “Hindsight is 20/20. I do empathize with the administration. It was hard to predict everything going up in flames so quickly.”