An enduring symbol of the public school system, the yellow school bus, rolls through town each morning, rain or shine, to collect children for educating.

But should a couple of drivers wake up sick, some Freeport students could find themselves waiting for a bus that never arrives.

In the face of a widespread labor shortage, Regional School Unit 5 and other Midcoast districts have leaned on substitute bus drivers, teachers, custodians and nurses to paper over vacancies in full-time positions. According to local superintendents, that strategy has left the ranks of fill-in substitutes dangerously thin.

With its only substitute bus drivers already covering full-time routes, RSU 5 warned parents in a Facebook post Friday that the bus might not be able to collect every student in time for school should a driver miss work with illness.

“We’re very aware that that’s a hardship for families,” Superintendent Jean M. Skorapa said. “But unfortunately, that’s where we’re at right now.”

The substitute shortage is just one facet of larger workforce issues in the education industry, said Tammy Mills, assistant professor of curriculum, assessment and instruction at the University of Maine’s College of Education and Human Development.

Even before the pandemic, which fueled widespread complaints of teacher burnout, the number of teachers completing educator preparation programs in Maine declined by 53% between 2010 and 2018, according to a 2019 report from the nonprofit Center for American Progress.

Districts such as RSU 5 – which currently has 14 unfilled education technician roles – and Regional School Unit 1 have leaned on their rosters of substitutes to fill those positions, either by officially hiring former subs as full-time workers or simply calling them in day by day. That’s kept classrooms running, said RSU 1 Assistant Superintendent Katie Joseph, but it’s made it difficult to find enough subs to fill in when teachers unexpectedly call in sick.

“We’re constantly moving folks around to look at where the need is,” Skorapa agreed. “But that creates an opening somewhere else.”

Though they often fly under the radar, substitutes play a unique role in maintaining everything from the classrooms to the custodial closets at public schools, according to Mills, a former teacher.

“What do you do with your middle schoolers or your class of first-graders for an entire day if you’re the human being in the classroom and you’re not going to be there that day?” Mills asked. “There’s no other industry, really, that has this kind of issue.”

Without subs on hand to step in for missing teachers, schools may have to shuttle students to other classrooms, sometimes even at other grade levels, she said. That can disrupt lesson plans, resulting in stressed teachers and wasted classroom time.

RSU 5 has done its best to come up with creative solutions, Skorapa said. Like a growing number of Maine districts, RSU 5 now employs a few salaried substitute teachers who report to work each day wherever they’re needed. In order to navigate a shortage of custodians and substitute custodians, Skorapa’s staff is now handling custodial work in the superintendent’s office, and the district is offering money to teachers who pick up cleaning shifts outside of their work hours.

Like Skorapa’s district, RSU 1 has recently raised substitute salaries and redoubled efforts to advertise open positions on Facebook, education job posting website Serving Schools, and the department’s webpage, as well as through word of mouth, according to Joseph.

The RSU 1 website lists openings for substitute nurses. The Brunswick School Department has postings for substitute van and bus drivers and custodians. Maine School Administrative District 75 is looking for substitute bus drivers. RSU 5 is hiring substitute nurses, bus drivers, custodians and kitchen assistants.

All four districts are looking for substitute teachers, a position that does not require a teaching certificate and which, according to frequent RSU 1 sub Tom Hines, offers the chance to do rewarding work on a flexible schedule.

“It’s a great part-time job,” Hines said. “Honestly, it’s tremendous.”