Black people who are married don't appear to live any longer than black couples who simply live together, suggesting marriage doesn't boost longevity for blacks the way it does for whites, according to a large national study led by Michigan State University.
"This finding implies that marriage and cohabitation have very different meanings for blacks and whites," said MSU sociologist Hui Liu, the study's lead researcher.
The study, in the Journal of Marriage and Family, is the first to document mortality differences between cohabiters and married people across racial groups in the United States.
The number of Americans who cohabitate (live together without being married) has increased dramatically in the past 50 years from 400,000 in 1960 to 7.6 million in 2011, census data shows.
Liu and Corinne Reczek of the University of Cincinnati studied national health survey data of nearly 200,000 people taken from 1997 to 2004. They found that white people who were married had lower mortality rates than whites who simply lived together.
However, there were no significant mortality differences between blacks who were married and blacks who cohabitated.
Liu said whites are more likely to see cohabitation as a trial marriage, which may mean lower levels of shared social, psychological and economic resources.
In contrast, among blacks cohabitation is more prevalent and is perceived as an alternative to marriage, meaning it may mirror the dynamics of marriage and promote health like marriage tends to do, Liu said.
In addition, because blacks tend to earn less money than whites, marriage may not confer the same degree of social and economic benefits for blacks as for whites, Liu said.
With the rapid growth of cohabitation, Liu said policymakers and scholars continue to question whether cohabitation and marriage promote well-being in equivalent ways.
"Although some researchers emphasize the similarity between cohabitation and marriage, others view the rising trend of cohabitation as a threat to population health," Liu said. "Our results on mortality differences by union status add to the mixed evidence on these debates."
Explore further: Study finds few well-being advantages to marriage over cohabitation