Revised 2010 census statistics shows that there are 131,729 same-sex married couples and 514,735 same-sex unmarried couples in the United States.
The US Census Bureau said that this was a revision of earlier results that overinflated the number of married couples to 349,377 due to a technical mistake.
The figures reflect an estimated 80% increase in the number of same-sex households in the US in the past decade.
Gay groups said that the statistics show the need for an end to same-sex marriage discrimination in the US.
“The number of gay and lesbian couples in committed, loving relationships, raising families together, continues to grow, leaving more and more families without the critical safety-net of marriage,” said Evan Wolfson, founder and President of Freedom to Marry.
“These findings also confirm that those who most need the support marriage offers – particularly in these tough economic times – live in the places with the fewest protections. The South is home to more gay parents than any other region in the nation,” said Wolfson.
“And yet, these families are not only discriminated against by their home states, which exclude them from marriage and bar even lesser protections such as civil union and domestic partnership, but are also targeted for an additional layer of discrimination from the federal government under the so-called Defense of Marriage Act (DOMA)”
Same-sex marriage is legal in the US states of Connecticut, Iowa, Massachusetts, New Hampshire, New York, Vermont, as well as the district of Washington, D.C. DOMA bars the US federal government from recognising these marriages.
Eleven other states offer some form of civil union or recognition of same-sex relationships.