The Census Bureau will begin counting gay married couples as families, reflecting changes in American society as more and more states allow such unions, the Washington Post reported.
"We're trying to make changes that reflect what's happening with American families," Rose Kreider, head of the bureau's fertility and family statistics, told the Post.
Gay married couples had previously been counted as unmarried partners, even when they reported themselves as married.
But in September, the bureau will publish an annual survey in which the same-sex spouses will for the first time be grouped with the country's 56 million families, according to the Monday report.
The category is not expected to get much of a bump from the same-sex addition, however, since the Census Bureau's most recent data from 2012 tallied only 182,000 gay married couples.
The bureau's move follows the June 2013 Supreme Court decision striking down the Defense of Marriage Act, which had restricted federal marriage benefits to heterosexual couples.
Gay marriage is increasingly supported by the American public.
According to a Gallup public opinion poll released last week, 55 percent of Americans now approve of same-sex marriage, the highest level ever.
In 1996, 68 percent of Americans opposed gay marriage, with only 27 percent in favor, Gallup said.
The Census Bureau first began collecting data on same-sex couples in 1990, when the category of unmarried partner was added, the Post said.
Judges in Pennsylvania, Oregon and Idaho recently struck down bans on same-sex marriage, bringing the total permitting gay marriages to 18 states and the US capital, Washington.