CONCORD, N.H. — As college students prepare to leave New Hampshire and Vermont for summer break, a recent national study raises questions about how many will return in the fall.

While both states rank very high in terms of the percentage of students who graduate within six years of starting at four-year public campuses, they also rank high in terms of students who finish in another state, according to the National Student Clearinghouse Research Center.

Its March report found that nationally, 6 percent of students who started at a four-year college in 2007 and completed their degrees by last year did so in a different state than where they began. New Hampshire and Vermont were among a dozen states where more than 10 percent of students took that path – in New Hampshire, it was 11 percent, and in Vermont, 13 percent.

Jim MacKay spent nearly four decades at the University System of New Hampshire, including 22 years as vice chancellor and four as chancellor before he retired last year. He says those numbers likely reflect the fact that the residential institutions that make up the university system each enroll at least 40 percent of their undergraduate population from outside New Hampshire. Those students pay considerably higher tuition, he said, and may be unable to afford it for their entire education.

“Thus, as many families continued to struggle through the recovery from the Great Recession, some – and particularly out-of-state students – made a financially driven decision to enroll elsewhere, and in many cases as in-state students in their home states,” said MacKay, who now heads the state Department of Education’s higher education division.

At the largest campus – the University of New Hampshire in Durham – 43 percent of this year’s undergraduate students are from out of state. The percentage is even higher at the University of Vermont, where 68 percent of the students come from out of state.

“We know that for UVM, many out-of-state students come from other states in the Northeast, and it is not uncommon for them to have applied and been admitted to their less expensive in-state options,” said John Ryan, director of the university’s Office of Institutional Research.

In-state tuition and fees at UNH totaled $16,500 this year, compared to $29,200 for out-of-state students. The University of Vermont charged in-state students $15,700 in tuition and fees, compared to $36,600 for nonresidents.

It’s unclear whether fewer students are crossing state lines since the economy improved.

Derek Thomson, 19, of Concord, transferred to Emerson College in Boston in January after spending a year and a half at Keene State College. In his case, he moved out of his home state and is paying roughly twice the tuition, but he hopes his post-degree earning potential will be similarly higher.

“Obviously, it was a huge financial jump, but I was willing to take that risk,” he said.

Thomson, who wants to go into film marketing, said Emerson always was his first choice, but he didn’t get in initially. While he liked Keene, he said, he didn’t click with his fellow film students and wanted more opportunities to gain experience outside the classroom.

Kate Luczko is the director of Stay, Work, Play, a nonprofit organization that encourages recent college graduates to remain in New Hampshire. She had not heard about students leaving the state before graduating, but said she frequently hears complaints that even in-state tuition is too expensive in New Hampshire, which may prompt students to transfer to cheaper schools in other states. She recently spoke to someone who lives in New Hampshire but found a college in Texas to be more affordable, she said.

Wherever they end up, students who start college in New Hampshire or Vermont are much more likely to graduate within six years. Vermont’s overall completion rate was 74 percent – the fifth highest in the nation – while New Hampshire ranked third at 78 percent.

“Where they complete the degree is less important than securing the critical set of skills, knowledge and engagement that will lead to post-graduation success,” MacKay said. “And the overall rate underscores the positive outcome of spending time matriculated at a USNH institution.”