In 1790, when U.S. marshals on horseback went trotting ’round post-colonial America to conduct the first U.S. census, Secretary of State Thomas Jefferson didn’t require that they ask whether two supposedly distant cousins of the same age and gender were in fact living out an “abomination before God.”

As the decades went by, the list of questions collected gradually increased, as did the country’s need for statistics to help people understand the changing landscape of the American melting pot and plan for growth. In 1810, the census was expanded to collect information on manufacturing and commerce. In 1850, it compiled information on churches, taxation, poverty and crime.

Fast forward to 1990. That year the census included a new category: “unmarried partner.” For the first time in the nation’s history, a simple category yielded a tangible number. There were 121,346 same-sex couples in the United States.

“In 1990, there was a lot of increased interest in counting cohabiting couples,” said Gary Gates, a senior research fellow with the Williams Institute for Sexual Orientation Law and Public Policy at UCLA. “Prior to 1990, you could call someone your roommate or you could call them an unrelated adult. There was no way to identify the status of someone who you were perhaps in a serious relationship with but you weren’t married [to].”

The Williams Institute recently released a report analyzing demographic data about gay, lesbian and bisexual people in the United States collected from the 2005 American Community Survey (ACS), part of the U.S. Census Bureau. The study includes estimates of the GLB population in states, major metropolitan areas and in congressional districts, noting a more than 170,000 increase in the number of self-identified same-sex couples nationwide.

Distributed annually, the ACS is designed to replace the census long-form questionnaire. Every 10 years when a census is conducted, about 80 percent of households receive a shorter census form containing about five questions, while the other 20 percent receive the more in-depth long-form.

“We get lots of really good information from [the long-form], but we’d only get it every 10 years,” Gates said. “The ACS is designed as a mechanism to replace the long-form so that we’ll have kind of detailed information updated on an annual basis.”

Gates noted that, unlike the standard census, the ACS is merely a sample of the population, similar to conducting a poll.

“There is a margin of error made in terms of the estimates that they produce,” he said.

However, as the U.S. Census Bureau moves toward replacing the long-form, the ACS is gradually reaching more households. Last year was the first time since the 2000 census that same-sex couples were counted.

“It’s the first time that we were able to update the numbers that we had from the census 2000,” Gates said.

Though it was possible to analyze differences between the data released between 1990 and 2000, a period during which the number of same-sex couples rose to 594,391, differences in the way the couples were counted made comparisons somewhat cloudy. In 1990, if a man referred to his partner as his husband or a woman claimed her partner as her wife, the bureau changed the gender to reflect an opposite-sex couple.

“They said that’s not possible, it must be that they made a mistake when they checked the sex,” Gates said. “In 2000, procedures that they used for counting same-sex couples are the same as these 2005 data, so we can really make legitimate comparisons.”

According to ACS data, between 2000 and 2005 the number of same-sex couples jumped from just under 600,000 to about 777,000 – a 30 percent increase. That increase is five times greater than the 6-percent rate of growth for the U.S. population, Gates said.

“Most likely, as stigma associated with same-sex partnering and homosexuality decreases, more same-sex couples are willing to identify themselves as such on government surveys,” Gates said. “This is especially remarkable considering that states offering formal recognition of same-sex relationships in the first half of this decade – Vermont, Massachusetts, Connecticut, California and New Jersey – saw relatively small gains in the number of gay couples.”

Surprisingly, the largest increase in the number of same-sex couples occurred in the Midwest. Predictably, Gates said, those increases weren’t due to a mass migration of gays and lesbians leaving urban centers to take up cattle ranching in Montana.

“Uniformly, across the nation, all the states sort of had some level of increase, which suggests that this is not as much mobility patterns as it is perhaps one of two things,” Gates said. “Either many more gay people have suddenly decided to become partners or, in fact, same-sex couples now are more willing to indicate the nature of their relationship on the survey. While both things might actually be happening, I think the latter is the more likely explanation.”

Gates said anti-gay ballot initiatives and laws banning recognition of same-sex marriage could be provoking more same-sex couples in red and Midwestern states to stand up and be counted (similar to the way Anita Bryant’s anti-gay “Save Our Children” campaign galvanized Florida’s gay population in the 1970s).

According to ACS data compiled by the Williams Institute, the District of Columbia had the highest percentage of gay, lesbian and bisexual adults in the population at 8.1 percent, compared to California with about 5.2 percent. However, California had by far the greatest number of GLB residents – 1,338,164 compared to Florida’s 609,219 and New York’s 592,337.

For the first time, the ACS also made it possible to estimate the size of the GLB population for current congressional districts. Not surprisingly, four California districts ranked among the top 10, including District 8 (San Francisco), at 16.6 percent; District 9 (Oakland), at 12.4 percent; District 45, (Palm Springs) at 10.8 percent; and District 53, (San Diego) at 10.5 percent. San Diego’s District 53 was the eighth largest congressional district in terms of numbers, with an estimated 46,791 GLB people.

However, the increase in same-sex couples between 2000 and 2005 was only 17 percent in California, far lower than the national average of 30 percent.

“That was true also for Massachusetts and other states that generally have pretty progressive laws around marriage,” Gates said. “Part of our intuition is that in states that are generally more favorable toward gay rights, there’s not as big of a closet there. More people are already kind of open…. Now we’re seeing some of these areas that were not as progressive in 2000 perhaps starting to catch up.”

The 2005 ACS data shows that in the city of San Diego there were 5,437 self-identified same-sex couples (up from 4,700 in 2000) and 61,945 individuals, or about 6.8 percent of the population. Of those couples, 3,700 were male and 1,737 female. The data also shows that for the North County region, encompassing Carlsbad inland to San Marcos, there were 8,759 same-sex couples and 102,016 individuals, about 4.9 percent of that region’s population, almost 2 percent lower than San Diego.

In terms of how the recent ACS data may impact Tuesday’s election, Gates found an interesting pattern nationwide.

“The seats with a Republican incumbent are the ones that have, on average, the higher numbers of gay people in the districts, which could have an interesting effect on the election,” he said. “The problem is we certainly don’t know whether willingness to be more open about your relationship on the ACS form correlates to voting behavior or willingness to vote. To the extent that it might suggest some increased level of political awareness or political involvement, it could be very interesting.”

In the last two presidential elections nationwide, about 75 percent of the people who identified as gay, lesbian or bisexual voted for Democrats Al Gore or John Kerry.

Kevin Davis, the San Diego Democratic Club’s information technology chair, has been compiling information on registered gay and lesbian voters for years from the San Diego County Registrar of Voters’ office. The information helps the club know where to send its voter guide during an election and how effective their efforts are.

According to the 2000 census, there were roughly 7,600 same-sex households in San Diego County (as opposed to the city), Davis said. The club currently has about 9,000 registered voters on its mailing list and about 8,000 households.

“Before every election, I go through the registration data and I find every same-sex household that I can,” Davis explained. “I try and find a household where there’s two people of the same sex living together, who are over college age and have a different last name. This election, we mailed to about 22,000 households. That’s roughly 8,000 households from our voter lists … plus 14,000 same-sex [couples] I found through the registration data.”

Davis also checks with the registrar to find out how many of the people who received their voter guide actually made it to the polls.

During the June primary election, only about 37.3 percent of the county turned out to vote, while among the 9,000 people who signed up for SDDC’s mailing list, turnout was 51.8 percent, about 15 percent higher than the general population. Among the 22,000 households who received the club’s voter guide based on demographic information, the turnout was only 33 percent.

“Maybe on the Democratic side people were kind of turned off because it was such a nasty fight between Westly and Angelides, and they decided to stay home,” Davis posited.

During the November 2005 election, which included San Diego’s hotly contested mayoral race between Donna Frye and Jerry Sanders and the governor’s array of unpopular ballot initiatives, 52 percent of county voters were driven to the polls, while 69 percent of the people on SDDC’s mailing list showed up.

Of the 9,000 individuals on SDDC’s list, 6,200 are Democrats, 1,600 declined to state their affiliation and 875 are Republicans.