Across the US, teachers are walking out of classrooms to demand higher salaries and better school funding. While most strikes are local and focused on issues specific to a district’s collective bargaining agreement, every now and then, educators across all or much of a state come together to protest broader issues. The well-known Red for Ed movement that sparked strikes in West Virginia, Kentucky, and Oklahoma last year was one such example.

These strikes have real economic impacts on students and educators. According to a new NBER working paper, teachers who strike secure salary increases of about $10,000 in inflation-adjusted dollars (about eight percent of their annual earnings), and working conditions improve: Class sizes decrease by about half on average, and expenditures on noninstructional staff increase by five to seven percent. The researchers note that these gains typically come from new revenues or expenditures, rather than from reallocated funds.

While a handful of studies have documented negative effects on student outcomes, most striking teachers end their walkouts with negotiated settlements that largely mitigate any harm caused by the strike. And while there is some evidence of short-term declines in math achievement, such drops are made up within a year.

The political effects of teacher strikes also have measurable implications on elections, as the NBER paper finds that they reduce Republican turnout and vote share in subsequent general elections in the affected districts. That finding is consistent with previous research that found similar electoral consequences for other labor actions, like unauthorized job actions or sickouts.