What's changed after 20 years of same-sex marriage in the US

Same-sex marriage supporters wear just married shirts while celebrating the U.S Supreme Court ruling regarding same-sex marriage on June 26, 2015 in San Francisco, California. (Photo by Justin Sullivan/Getty Images)

Friday marks 20 years since Massachusetts issued the first marriage licenses for same-sex couples, and according to a new report – the results have been overwhelmingly positive.

An analysis from RAND, a nonprofit research organization, and UCLA reviewed nearly 100 studies that looked at the effects of same-sex marriage. They found "significant benefits to same-sex couples and no harm to different-sex unions."

Following the Massachusetts decision in 2004, same-sex marriages were sanctioned in several other states over the next 11 years before the U.S. Supreme Court extended same-sex marriage nationwide in 2015 with the Obergefell v. Hodges case. 

Same-sex marriage in the US

The report says about 70 percent of Americans now support same-sex marriage.

"Some of those who opposed the granting of marriage rights to same-sex couples predicted that doing so would undermine the institution of marriage, resulting in fewer couples marrying, more couples divorcing, and an overall retreat from family formation," study coauthor Benjamin R. Karney, a UCLA psychology professor and adjunct researcher at RAND, said in a prepared statement. "Overall, the fears of opponents of same-sex marriage simply have not come to pass."

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The study found that after states legalized marriage for same-sex couples, the number of different-sex marriages increased as well.

"We find no evidence for a retreat from marriage," said Melanie A. Zaber, coauthor of the report and a RAND economist. "In fact, there is evidence suggesting that by extending marriage rights to a greater number of couples, interest in marriage increased. And that finding isn't limited to same-sex couples—this is also true for the broader population."

Effects on LGBT people and their children

Researchers from RAND and UCLA analyzed 96 studies that examined same-sex marriage and how it affects LGBT people, their children and the general public.

Analysis showed that the "marriage benefit," or the positive effects of marriage on one’s overall life, extended to same-sex couples once they were given the right to marry.

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"This includes lower psychological distress as compared to same-sex couples with other forms of legal status or no legal status," and the physical health of LGBT residents improved after same-sex marriage was legalized. Researchers credit an increase in health insurance, declining STD rates and lower amounts of substance use as reasons for the quality of life changes.

"When states legalized marriage for same-sex couples, same-sex households in those states experienced more stable relationships, higher earnings, and higher rates of home-ownership," the report said.

Rates of unmarried couples cohabitating declined in the years following same-sex marriage, and no increase in divorce rates.

"The only changes we detect are suggestive of a renewed salience of marriage among the broader public," Zaber said. "There is no empirical basis for concerns that allowing same-sex couples to marry has negatively affected different-sex couples and families."