D.C. has retained its status of having the highest number of same-sex couples per 1,000 households compared to all 50 states, and it had a 40 percent increase in the number of people identifying themselves as same-sex couples since 2000.

Those are among the findings of newly released data from the 2010 U.S. Census as analyzed by the Williams Institute, a think tank affiliated with the University of Southern California at Los Angeles. The institute specializes in LGBT related issues.

The data show that Maryland had a 51 percent increase in the reported number of same-sex couples from 2000 to 2010 and Virginia saw a 49 percent increase in same-sex couples for that same ten-year period.

“The increases are far higher than population increases,” said Williams Institute official Gary Gates. “So we feel most of the increases we’re seeing in states, cities, and counties are attributable to more people reporting they’re a couple than ten years ago.”

The 2010 Census data show that 5,146 D.C. households declared themselves as being headed by same-sex couples, representing a rate of 19 same-sex couples per 1,000 households.  In the 2,000 census, 3,678 households in the District identified themselves as same-sex couple households.

Of the 5,146 D.C. same-sex households reported in the 2010 Census, 72 percent were gay male couples and 28 percent lesbian couples.

Ninety percent of the same-sex households reported in the 2010 Census for D.C. were not raising children compared to just 10 percent who reported they were raising children, according to the Williams Institute analysis of the data.

The Williams Institute analysis also shows that the highest concentration of same-sex couples in D.C. reported in the 2010 Census were in census tracks in neighborhoods of Logan Circle, Dupont Circle, Shaw West, Shaw East, and an area bounded by “Morrow Drive to Piney Branch Parkway, N.W., Rock Creek and 16th Street, N.W.”

The data show that the highest concentration of same-sex couples raising children were female couples living in mostly black neighborhoods in the far Southeast and far Northeast sections of the city.

The D.C. data were released Thursday by the Williams Institute, which is known officially as the Williams Institute on Sexual Orientation and Gender Identity Law and Public Policy. The Williams Institute has analyzed Census data pertaining to same-sex couples since the 2000 U.S. Census, when the  census first began counting them.

The 2010 Census data released by the Williams Institute show these figures for same-sex couples living in D.C. area suburban jurisdictions:

• Montgomery County, Md. – 2,911 same-sex couples; 8.2 same-sex couples per 1,000 households
• Prince George’s County, Md. – 2,525 same-sex couples; 8.3 same-sex couples per 1,000 households
• Fairfax County, Va. – 2,783 same-sex couples; 7.1 same-sex couples per 1,000 households
• Arlington, Va. – 1,328 same-sex couples; 13.5 same-sex couples per 1,000 households
• Alexandria, Va. – 941 same-sex couples; 13.8 same-sex couples per 1,000 households
• Baltimore, Md. – 3,226 same-sex couples; 12.9 same-sex couples per 1,000 households

Gates said the data the institute has analyzed so far show that the number of same-sex couples reported nationwide has increased by about 50 percent between 2000 and 2010. Gates said population growth and migration of LGBT people to certain locations accounts for some of the increase.

But he said most of the increase appears to be due to a decision by far more same-sex couples to self-identify while filling out the 2010 U.S. Census questionnaire, which was sent to all U.S. households.

Although D.C.’s rate of 19 same-sex couples per 1,000 households is the highest among the 50 states, several cities have rates far higher than D.C. if D.C. were to be viewed as a city.

Provincetown, Mass., a gay vacation destination with a sizable population of LGBT people living there year-round, leads the nation among cities with 50 or more same-sex couple households, with a rate of 163 same-sex couples per 1,000 households, Gates said.

The city of Wilton Manor, Fla., long known as an LGBT-friendly enclave next to Fort Lauderdale, came in second among cities in the 50 or more same-sex household category, with a rate of 140 same-sex couples per 1,000 households, according to Gates.

Palm Spring, Calif., came in third, with 115 same-sex couples per 1,000 households, Gates said.

In a development that appears to represent an LGBT population shift more than a greater degree of gay couples “coming out” in the Census questionnaire, Gates said the city of Rehoboth Beach, Del., came in fourth place in the category of same-sex couples in cities with 50 or more same-sex households.

Gates said the 2010 Census data show Rehoboth, a popular LGBT resort town, has a rate of 107 same-sex couples per 1,000 households. Gates noted that the actual number of same-sex couple households counted in the 2010 Census for Rehoboth was 81, an increase of 47 couples over the 34 same-sex couples that declared themselves in the 2000 Census.

“I think what you see there is this kind of movement from vacation home to actual residence for a lot of people,” Gates said. “I think in the last decade people made a lot on the real estate market in D.C. and bought vacation properties in Rehoboth. And I think now quite a few of them have moved there.”

Steve Elkins, an official with Camp Rehoboth, an LGBT advocacy group and community center in Rehoboth, said the census figures don’t surprise him.

“You see it every day. We’re in all walks of life,” he said, from local politics to the outlet malls.