Nearly half of Americans support same-sex marriage and the proportion who are accepting of homosexuality is increasing, University of Chicago researchers said on Wednesday.
The results show a clear "trend toward greater tolerance regarding homosexuality," said Tom Smith of the National Opinion Research Center at the University of Chicago.
The Center's General Social Survey showed that support for same-sex marriage rose from 11 percent of Americans in 1988 to 46 percent approving of it in 2010. For the first time supporters outnumbered the 40 percent who were opposed.
Six states and the District of Columbia allow same-sex marriage. Thirty-nine states specifically ban it.
Younger American adults surveyed were much more accepting of same-sex marriage than older Americans, illustrated by support among 64 percent of those under 30 compared to 27 percent among those older than 70.
The survey, which has been taken every other year for 40 years, found 86 percent supported a gay person's right to speak before a public audience, 24 points higher than in 1972. Also, 84 percent supported allowing gays to teach at colleges or universities, up from 48 percent in 1973.
The change in acceptance of homosexuality began in the late 1980s, the researchers said. In 1987, 75 percent felt same-sex relations were "always wrong," but that number fell to 43.5 percent in 2010.
The U.S. Census Bureau on Tuesday estimated the number of same-sex married couple households in the United States at 131,279.