The bureau said its revised figures from the 2010 Census put the number of married same-sex households at 131,729, down from the original count of 349,377. The number of same-sex unmarried partner households dropped by a smaller percentage, from 552,620 to 514,735.
The updated numbers are closer to the results of the 2010 American Community Survey, the bureau said in a release. That survey estimated gay and lesbian married couples at 152,335 and same-sex unmarried partners at 440,989.
Census Bureau said it made the changes after its staff discovered an inconsistency in responses in the 2010 Census summary file statistics that artificially inflated the number of same-sex couples.
The bureau said statistics on same-sex couple households are based on answers to two questions on the Census and ACS questionnaire: relationship to householder and the sex of each person. When data were captured for these two questions on the 2010 Census door-to-door form, the wrong box may have been checked for the sex of a small percentage of opposite-sex spouses and unmarried partners. Because the population of opposite-sex married couples is large and the population of same-sex married couples is small, an error of this type artificially inflates the number of same-sex married partners, the bureau said.
The bureau said its staff created a new set of estimates to provide a more accurate way to measure same-sex couple households.
"We understand how important it is for all groups to have accurate statistics that reflect who we are as a nation," Census Bureau Director Robert Groves said. "As scientists, we noticed the inconsistency and developed the revised estimates to provide a more accurate portrait of the number of same-sex couples. We're providing all three -- the revised, original and ACS estimates -- together to provide users with the full, transparent picture of our current measurement of same-sex couples."