Gates, an expert on the geography and demography of the LGBT population, spoke at the National Lesbian and Gay Journalists Association conference last week in Philadelphia, along with Lanette Swopes, of the Census Bureau's Philadelphia region.
"These latest numbers especially show that same-sex couples live everywhere, in rural and urban areas," he said. "Legislators can no longer argue that LGBT issues are not relevant in their populations."
Gates' analysis of the 2010 census numbers shows that female same-sex couples outnumber male, 60 percent to 40 percent. And while the majority of same-sex couples (78 percent) are not raising children, of those who are, 3.2 percent of male same-sex couples live in poverty, as compared with 1.2 percent of their heterosexual counterparts
And 40 percent of same-sex couples rearing children are African Americans.
A number of socially conservative states, such as Texas, Louisiana, Alabama, and Wyoming, rank among those with a high percentage of same-sex couples raising children.
"Not that there are so many gay couples there," Gates said, "but they're just more likely to have had children at a very young age - before coming out. And now they're living in places with few legal protections."
"What we see is that where gay parenting is more common is where the laws against gay couples are the worst," Gates said.
Using the census figures and other reliable population-based studies, Gates puts the LGBT population at nine million, or roughly 4 percent of the U.S. population.
So it is ironic, if nothing else, that Americans on average think there are more gay people, Gates says.
A May 2011 Gallup poll showed that Americans estimate the size of the LGBT population at 25 percent - not the 4 percent the estimates found.
"That's a good sign," Gates said. "That tells me most Americans have LGBT people around them; they know them as people. And that's a huge change from 25 years ago when many people denied the community even existed."
The Census Bureau started counting same-sex couples as "unmarried partners" in 1990 (and found 145,130), but it has taken several tries, Swopes said, to tweak its forms for clarity and for members of the LGBT community to feel comfortable with self-reporting.
Swopes, who was part of the effort to persuade LGBT people to participate in the 2010 census, said data collection helps to allocate funds properly for school lunches, health care, and housing.
Now other federal agencies are planning studies that will ask about individuals - not just couples.
In April, Kathleen Sebelius, secretary of the Department of Health and Human Services, said the agency would begin to ask about gender identification and sexual orientation on all of its surveys - two aspects the census never asks about. And Gates is involved in designing those studies.
Collecting same-sex-couple data has been challenging, Swopes said.
For starters, terminology is an obstacle. Many same-sex couples don't use the terms husband and wife, and others acknowledge that a civil union is not a federally recognized marriage.
All census questions are mandated by Congress, Swopes says, and the questions primarily look at households, not individuals.
Contact Inquirer staff writer Dianna Marder at 215-854-4211 or email@example.com. Read her recent work at http://go.philly.com/diannamarder and follow her on twitter, @marderd.