Twenty Years of Legal Marriage for Same-Sex Couples in the United States

The Research Question

Prior to the Supreme Court's Obergefell v. Hodges decision in 2015, the United States had been divided by heated debates over the merits of legalizing marriage for same-sex couples. Those who were in favor argued that granting same-sex couples access to marriage would strengthen commitment for same-sex couples, extend the financial benefits of marriage to same-sex households, and improve outcomes for children being raised by same-sex parents. Those who were opposed argued that granting legal status to marriages between same-sex partners would alter the foundation of marriage and thereby diminish its value for different-sex couples, ultimately harming children by making them less likely to be raised in stable, two-parent families.

It has now been 20 years since Massachusetts became the first state to issue marriage licenses to same-sex couples in May 2004. The consequences of extending legal recognition to same-sex couples need no longer be a topic of speculation and debate; researchers have had two decades to study the consequences of legalizing marriage for same-sex couples on lesbian, gay, bisexual, and transgender (LGBT) individuals; their children; and the general public.

The broad goal of this study is to document those consequences. We pursued this goal in two ways. First, we conducted a comprehensive review of the existing research literature on the effects of legalizing marriage for same-sex couples. Second, we conducted new analyses to evaluate the specific prediction that rates of marriage, divorce, and other aspects of family formation would be adversely affected by marriage policies that afforded equal treatment to same-sex and different-sex couples.

Approach

For the evidence review, we conducted a comprehensive search of existing empirical studies of the impacts of legal marriage for same-sex couples on LGBT individuals, their children, and the general population. The 96 studies identified in our search employ a wide variety of methods and designs, including cross-sectional surveys, repeated comparisons across state policy environments, and longitudinal research. Furthermore, this substantial literature incorporates diverse perspectives and scholarly disciplines and examines a broad variety of outcomes potentially influenced by legal marriage for same-sex couples.

For the new causal analyses, we drew on multiple national datasets to evaluate how changes in marriage policy across states relate to changes in marriage rates, divorce rates, and cohabitation rates in the general population. We also examined attitudes toward marriage among young adults. For these analyses, we used the latest advances in difference-in-differences methodology to estimate the effects of state-level policy changes in the legalization of marriage for same-sex couples on each outcome. We replicated our analyses across a variety of data sources with different sampling structures and tested the sensitivity of our findings across a variety of approaches to modeling each outcome of interest.

Key Findings

Evidence Review

Across 96 published or soon-to-be published empirical studies conducted over the past 20 years, the consequences of extending marriage and other forms of legal recognition to same-sex couples have been consistently positive for same-sex couples and LGBT individuals, their children, and the general population.

For LGBT individuals and same-sex couples—the populations who were most directly affected by legalizing marriage for same-sex couples—the benefits of access to legal marriage were unambiguous. Without exception, research has found that the well-documented advantages associated with marriage in different-sex couples are reliably observed in same-sex couples as well:

• When states legalized marriage for same-sex couples, same-sex households in those states experienced more-stable relationships, higher earnings, higher rates of homeownership, and better preparation for retirement and end-of-life care.
• When states legalized marriage for same-sex couples, the physical health of LGBT individuals in those states improved, demonstrated by higher levels of health care use, higher levels of health insurance coverage, and declining rates of sexually transmitted infections and problematic substance use.
• Multiple studies have found that married same-sex couples report lower psychological distress than same-sex couples with other forms of legal status (i.e., civil unions or domestic partnerships) or no legal status.
• After states legalized marriage for same-sex couples, social support, particularly family support, improved for LGBT individuals and perceived stigma declined.
• When states legalized marriage for same-sex couples, sexual orientation–motivated hate crimes and employment discrimination against LGBT individuals declined.
• In contrast, when states banned marriage for same-sex couples, LGBT residents of those states reported higher anxiety and lower life satisfaction than residents of states without bans, even after controlling for other elements of the state political climate.

Although extensive research has consistently found that children raised by same-sex couples experience similar levels of well-being to children raised by different-sex couples, few studies have directly examined the effects on children when their same-sex parents are granted access to legal marriage. Of the studies we identified that addressed this question, all found that children of same-sex couples benefited when their parents were granted access to legal marriage:

• Access to legal marriage greatly reduced or eliminated disparities between the children of same-sex couples and the children of different-sex couples, with respect to access to health insurance and progress through school.
• After controlling for socioeconomic variables, there were no reliable differences in the emotional and physical health of children of married versus cohabiting same-sex parents.

Despite the concerns of opponents of legalizing marriage for same-sex couples that doing so would bring harm to different-sex couples and households, the existing research has found the effects of legal access to marriage for same-sex couples to be uniformly beneficial for these groups as well:

• Although some feared that judicial and legislative actions granting same-sex couples access to marriage would provoke a backlash in public opinion, no evidence of lasting negative changes in public opinion have been found. On the contrary, nationally representative polls find that more than 70 percent of Americans now approve of marriage for same-sex couples.
• When states legalize marriage for same-sex couples, state-level rates of syphilis, HIV, and AIDS fall significantly, resulting in billions of dollars in savings to the nation's health care system each year.
• Extending legal recognition to same-sex couples affects state-level adoption rates, which rise by between 4 percent and 6 percent after marriage between same-sex partners becomes legal.
• There is some evidence that the economies of states that granted legal status to same-sex couples improved as a result, as measured by higher rates of patents awarded in those states and higher market values for corporations headquartered in those states after marriage for same-sex couples was legalized.

As notable as these significant findings are, it is also worth noting what has not been found in the past two decades of research. Across 96 studies conducted over 20 years, the existing literature has not identified any reliable adverse consequences of policies granting same-sex couples access to legal marriage. In particular, prior research has not found any evidence of any effect of these policies on trends in family formation among different-sex couples.

New Analyses

To evaluate the specific impact of policies legalizing marriage for same-sex couples on family formation among different-sex couples and the general population, we leveraged advances in research methodology and multiple data sources to examine the causal effects of such state-level policy changes between 2000 and 2014 on different-sex couples' marriage rates, divorce rates, and cohabitation rates.

• We found no evidence of a retreat from marriage. In fact, the only evidence of change that we discovered is a possible increase in marriage resulting from legalization of marriage between same-sex partners. Importantly, we can identify that this is not driven solely by newly marrying same-sex couples.
• When we compared states that legalized marriage for same-sex couples earlier with states that legalized it later (but still pre-Obergefell), we found no evidence that our results are unique to the states that were earlier adopters of issuing marriage licenses to same-sex couples.
• In the datasets in which we were able to examine cohabitation, there is no evidence of a statistically significant increase in cohabitation by unmarried different-sex couples, and there is limited evidence of a decline.
• We similarly found no consistent evidence of an increase in divorce as a consequence of legalizing marriage for same-sex couples, regardless of potential changes in who was getting married.
• Finally, across a variety of attitudes toward family formation assessed among high school seniors, we found no evidence of a negative shift in attitudes toward the institution of marriage, and we observed some evidence of an improvement.

Opponents of granting marriage licenses to same-sex couples predicted that doing so would undermine the institution of marriage and result in fewer couples marrying, more couples divorcing, and an overall retreat from family formation. In examining this question, we used analytic approaches designed to maximize the chances of observing a statistically significant effect, if one exists. Yet these analyses reached the same conclusions as the other studies of this issue: Permitting legal marriage among same-sex couples had no adverse effects on marriage, divorce, or cohabitation among different-sex couples. On the contrary, the few significant effects observed in our analyses suggest a slight increase in marriage rates and potentially improved attitudes toward marriage after same-sex couples were granted legal status by a state.

This research was sponsored by Centerline Liberties and conducted in the Social and Behavioral Policy Program within RAND Social and Economic Well-Being.