A student has his temperature checked at a school in Orange, California, on Aug 24.(Photo: Getty Images)

As the United States celebrated Labor Day on the last three-day holiday weekend of the summer, coronavirus cases are reported to be rising in 22 of the 50 states, and one reason is the reopening of schools and colleges.

Colleges are dealing with the arrival of students from some places with high infection rates into dormitories and off-campus housing－and some schools are seeing widespread partying on and off campus.

Schools have set up testing centers in stadiums, parking lots and gymnasiums. Some, like George Mason University in Virginia, sent kits to students at home and asked them to send back specimens on throat swabs, to be then sent to labs.

Protocols and procedures have been imposed at virtually every school, from daily temperature checks and contract tracing to having students sign pledges to follow masking and social distancing rules or face disciplinary measures, including expulsion.

The regulations are aimed at not only protecting students and staff, but also the communities where the schools are located. Those that have in-class instruction, even if on a limited basis, want to avoid moving entirely to online instruction or sending students home, losing millions of dollars in revenue.

"For the most part, everyone I've been talking to has a plan. But to quote Mike Tyson, 'Everybody has a plan until they get punched in the face,'" said Scott Schneider, a lawyer in Austin, Texas, and consultant on higher education.

"It's unlikely that any school in the US will come out of the fall semester without a coronavirus case," he said.

Thousands of San Diego State University students were ordered on Saturday to stay in their dorms until Tuesday morning because of an outbreak. The university has reported 120 cases so far.

About 2,600 students live on campus from among the 35,000 enrolled at the university. The lockdown order follows a move to online classes several days ago.