Schools in the United States are welcoming back students to classrooms this autumn. But they are facing a new problem: a shortage of teachers and school workers. Districts have faced shortages before, but many now say it is the worst it has ever been. The country’s public schools have struggled for years with teacher shortages, especially in math, science, special education and languages. But the COVID-19 crisis has worsened the problem. The pandemic has led to an increase in retirements and resignations. Districts across the country are reporting teacher shortages. In South Dakota, one district started the school year with 120 unfilled teacher positions. Across Texas, the main districts in the cities of Houston and Waco reported hundreds of teacher openings at the start of the year. Many schools across the country have had to close classrooms because of a lack of teachers. In Michigan, Eastpointe Community Schools moved its middle school back to online learning last week because it does not have enough teachers. The small district north of Detroit has 43 positions open one quarter of its teachers. When several middle school teachers resigned last week, the district started teaching online classes to avoid sending in inexperienced substitute teachers, said spokeswoman Caitlyn Kienitz. “This is obviously not ideal, but we’re able to make sure they’re getting each subject area from a teacher certified to teach it,” Kienitz said. The National Education Association surveyed 2,690 educators in June. Thirty-two percent said the pandemic drove them to leave teaching earlier than expected. Another survey by the Rand Corporation found that teachers had high levels of stress and were three times more likely than adults in other professions to experience depression.