Certification rules can make moving to a new state a serious hassle for teachers.

That might explain a recent finding: Teachers are significantly less likely to move between states than others with similar jobs — and past research suggests that students suffer as a result.

The study, which uses national data from 2005 to 2015 and was released this week through the National Bureau of Economic Research, appears to be the first to document how frequently teachers move states compared to those in other occupations.

Teaching stands out: Relative to jobs requiring a similar level of education, teachers were 45 percent less likely to move to different state, but only 5 percent less likely to move a long distance within a given state. This suggests that teachers aren’t averse to moving — there are just strong incentives to not cross state lines.

That “may limit the ability of workers to move to take advantage of job opportunities,” the researchers write. That’s consistent with research on the Oregon–Washington border, where teachers were more likely to move long distances in their own state than shorter distances across the state line.

Winning permission to teach in a new state sometimes requires re-taking coursework and taking new certification exams. There may be good reasons for that — for instance, states that are particularly attractive to teachers may want to maintain especially high standards but it’s also a complicated process to navigate.

“Web-surfing became my life, through hard-to-navigate state department of education websites and portals that looked like something I had created back in my college sophomore computer science class in 1998,” wrote one teacher in a recent piece for Education Week, describing her efforts to meet new requirements after moving from Florida to Massachusetts.

This matters because the rules may keep teachers who move from re-entering the classroom altogether. A national survey found that among people who had left teaching but were considering re-entering the classroom, 40 percent identified “state certification reciprocity” as a key factor in their consideration.

That, in turn, affects students. One analysis has found that schools near state borders perform consistently worse on standardized tests — perhaps because certification and other rules limit the pool of potential teachers. Research has also shown that teachers perform best when they find a good “fit” with a school, and certification rules may make that harder.

Certification rules are not the only factor in play. Teachers’ decisions may also be influenced by retirement plans that aren’t easily portable and rules that would require them to give up seniority and tenure protections when they move.

It doesn’t have to work this way. The study finds that people in other professions, like medicine, are freer to move and have certifications that easily transfer between states. But the idea of a national “bar exam” for educators hasn’t ever gained traction.

A handful of states have agreed to accept one another’s certifications, and a provision in ESSA would allow federal money to go toward the efforts.

As for the teacher, Megan Allen, who struggled with Massachusetts’ rules — and had 10 years of experience and a National Board certification? She left public education as a result. “I didn’t feel like I was valued for any of the expertise that I had earned, worked hard for, and proved,” she wrote.