From a U.S. Census Bureau Summary:
The U.S. Census Bureau released today new statistics on same-sex married couple and unmarried partner households. According to revised estimates from the 2010 Census, there were 131,729 same-sex married couple households and 514,735 same-sex unmarried partner households in the United States.
The results of the 2010 Census revised estimates are closer to the results of the 2010 American Community Survey (ACS) for same-sex married and unmarried partners. The 2010 ACS estimated same-sex married couples at 152,335 and same-sex unmarried partners at 440,989.
The new, preferred figures revise earlier estimates of same-sex unmarried partners released this summer from the 2010 Census Summary File 1 because Census Bureau staff discovered an inconsistency in the responses in the 2010 Census summary file statistics that artificially inflated the number of same-sex couples. In addition, a breakdown of couples who reported as same-sex spouses is now available. The summary file counts originally showed that there were 349,377 married couple households and 552,620 same-sex unmarried partner households.
The 2010 Census preferred estimates have been peer-reviewed by Gary Gates, a demographer with the UCLA School of Law’s Williams Institute on Sexual Orientation Law and Public Policy, by Philip Cohen, a professor of sociology at the University of North Carolina at Chapel Hill, and by Megan Sweeney, professor of sociology at UCLA. These experts concluded the methodology behind these revised estimates was sound.