COLUMBUS, Ohio — Historically, segregation has played a significant role in determining lifespan in the United States, a new study finds.

Researchers at Ohio State University looked at historical data from the state of North Carolina covering the years 1909 to 1975, finding that while segregated areas had higher mortality rates overall, certain demographics actually lived longer in such locales.

For instance, one of the study’s main findings was that during the period examined, some blacks actually lived longer in segregated environments.

“The study shows that the effects of segregation apply not only to the present, but also to the past,” says Trevor Logan, the study’s co-author in a university press release. “More importantly, we found that segregation was related to health outcomes in rural as well as urban areas.”

All in all, whites lived 10 years longer than blacks on average in the U.S. during the six-plus decades studied, but whether one lived in an urban or rural area had the ability to change this figure.

For blacks, living in an highly-segregated urban area — as opposed to one with an average level of segregation — was associated with an increase in lifespan: five years for African American females, and 10 years for black males.

While these outcomes were less pronounced for blacks living in segregated rural areas, they trended in the same direction.

Logan speculates that segregation could have helped blacks avoid infectious disease in the pre-antibiotic era.

“In a period with a lack of access to quality health care, especially for black people, less exposure between races could have had large, positive effects on black health,” he explains.

Meanwhile, whites in segregated areas lived shorter lives than their peers as a whole, although the opposite appears to have been true of whites living in segregated areas that were urban.

As for infant mortality, although blacks experienced higher rates than whites in the early-to-mid 20th century, segregation was not a cause of the disparity.

“Our results suggest that segregation mattered in rural areas, as well as urban areas,” Logan concludes. “And the effects of segregation were evident long before the Great Migration of African Americans to urban centers.”

The study’s findings were published in the journal Social Science and Medicine.