New research continues to show that marriage is connected to longer life.

A new study from researchers at Michigan State University and the University of Cincinnati compares mortality rates between married and cohabiting individuals. Researchers found that among some groups, married individuals have lower mortality rates compared to individuals who cohabit.

Previous research shows that when compared to those never married, divorced, or widowed, those who are married experience lower mortality rates. For example, one study reveals that, over the course of eight years, the odds of mortality were nearly 60 percent higher for never-married individuals, roughly 30 percent higher for divorced or separated individuals, and nearly 40 percent higher for widowed individuals. The connection between marriage and longer life shows up in international studies as well. (continued below chart)

The link between marriage and longevity is likely connected to the generally better levels of health—both physical and psychological—of married individuals. Nearly 90 percent of married adults report being in good or very good health: a greater percentage compared to their non-married peers. Additionally, married people are less likely to experience health problems or take part in risky health behaviors (smoking, drinking, etc.).

Marriage is also connected to improved recovery from illness. A 2011 study revealed that married individuals are about twice as likely to survive within five years of having heart surgery as compared to unmarried individuals. Similarly, another study the same year found that married men and women were 250 percent more likely to be alive 15 years after coronary artery bypass surgery than their unmarried counterparts.

Marriage promotes the positive outcomes of children and society as a whole. Marriage is the greatest protector against child poverty, and children from married-parent families are more likely to thrive on a variety of measures. As adults and children thrive, societies are able to prosper.

Sadly, marriage rates are declining in the U.S. As the marriage rate declines, fewer will reap the many benefits this institution provides. Policies to promote and support marriage are crucial to ensuring the strength of the nation.