School districts across the country are grappling with a shortage of school bus drivers after some drivers resigned over worries about being exposed to young unvaccinated children and others quit over requirements that they get a Covid-19 vaccine.

The shortage, in every region of the country, has left some students without district-provided transportation, and others with long commutes to and from school at a time when schools are returning to in-person classes after a hybrid or remote pandemic year.

School districts and bus-contractor companies are offering signing bonuses, pay increases and even full-time benefits in hopes of attracting more applicants.

“The pandemic completely, absolutely 100% exacerbated what was already a difficult industry to be able to recruit and find individuals to come work and transport children,” said Danielle Floyd, general manager of transportation services for the School District of Philadelphia.

A recently published nationwide survey of about 1,500 school transportation professionals, which was conducted by three national transportation associations, found that roughly two-thirds of all respondents said that the bus-driver shortage is their No. 1 problem or concern.

About half of survey respondents described their driver shortage as “severe” or “desperate.” Half of survey respondents said the rate of pay is a major factor affecting their ability to recruit and retain drivers, and others cited the length of time it takes to train and license drivers.

Some districts found themselves facing sudden resignations after instituting vaccine mandates. “There’s no doubt in my mind that those mandates will affect the driver pool,” said Curt Macysyn, executive director of the National School Transportation Association.

Last month, Chicago Public Schools scheduled pickup times to start approximately 15 to 30 minutes earlier than prior years due to a shortage of about 420 bus drivers.

In mid-August, the district announced that all employees would need to submit proof of full vaccination by Oct. 15. The week of Aug. 23, approximately 10% of bus drivers resigned, which bus vendors said was “likely driven by the vaccination requirements.” Approximately 70 drivers resigned on Aug. 27 alone. The shortage meant the district couldn’t provide transportation for about 2,100 students.

The district is offering families transportation stipends of $1,000 for the first two weeks, and $500 the following months for the 2,100 students without transportation, as well as for students who are affected by longer route times.

School districts and bus-contractor companies are offering signing bonuses, pay increases and even full-time benefits in hopes of attracting more applicants.

Photo: Iris Samuels/Associated Press

Nashondra Henderson’s 16-year-old son no longer has transportation. Ms. Henderson’s son, who is a junior at the district’s Roberto Clemente Community Academy, has autism. The school district called her on Sunday, the day before school reopened for the fall, to inform her that the school bus wouldn’t be dropping off or picking up her son. No one could say when his busing will be restored, she said. Ms. Henderson has six other children whom she has to help get off to school, and said her son can’t take public transportation on his own.

Because there is no bus, and Ms. Henderson is unable to get him to school, he is staying at home for now and doing remote learning. She said the district offered her a $1,000 stipend for the first two weeks, and $500 a month after. “I don’t need the $500 a month; I need my son to get to school,” she said.

The district said it is giving priority to routes for diverse learners, whose families will be provided the stipend in the interim, and will be offered bus transportation in the near future. The district is working with families to solve the problem, it said, in a statement.

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Part of the problem schools face is competition with companies like Amazon.com Inc. and Uber Technologies Inc. for drivers, says John Benish Jr., president of Cook-Illinois Corp., a school bus contractor that services more than 200 school districts.

Mr. Benish said some potential bus drivers are wary of coming into contact with large groups of children, many of whom aren’t eligible to be vaccinated. Others, he said, are opposed to the vaccine and might not come into work if it is mandated. The company is about 20% short of necessary drivers at some of its locations, and the problem is expected to persist until after the holidays, he said.

“It’s just going to be a while to get this shaken out," he said.

Write to Allison Pohle at Allison.Pohle@wsj.com