John M. Glionna / Los Angeles Times

A new study tracking the percentage of gay and lesbian adults in America has established a first-ever demographic atlas of the group, finding that populations range from a low of 1.7 percent of total population in North Dakota to a high of 10 percent in the District of Columbia.

The study, conducted by Gallup Poll Editor-in-Chief Frank Newport and UCLA scholar Gary Gates, is the largest population-based survey to include a state-by-state measurement of lesbian, gay, bisexual and transgender identification.

“This is simply new ground — these are not just new statistics; they are the only estimates we have of these people at the state level,” Gates, a demographer at the Williams Institute at UCLA, which studies sexual orientation, said. “There is no other data out there to verify these numbers, which constitute a significant advancement in our understanding of the LGBT population.”

In all, more than 206,000 adult Americans were surveyed for the expansive study, with 41 of the 50 states including polling samples that exceeded 1,000, researchers said. Participants responded to the question, “Do you, personally, identify as lesbian, gay, bisexual, or transgender?” in surveys conducted between June 1 and Dec. 30, 2012.

Only eight states had less than 1,000 completed interviews, including the lowest sample size of 613 in Alaska.

Analyzing the state-by-state breakdown, researchers found that while LGBT communities are clearly present nationwide, their visibility is generally higher in states with greater levels of social acceptance and supportive LGBT legal climates.

Researchers said their results defied stereotypes that portray the LGBT community as heavily grouped in urban centers. With the exception of the District of Columbia, LGBT populations range 3.4 percentage points nationwide, with a low of 1.7 percent in North Dakota to 5.1 percent in Hawaii.

State laws

With the exception of South Dakota, each state with LGBT populations of 4 percent and higher has laws prohibiting discrimination based on sexual orientation and gender identity. These states have also taken steps toward more LGBT equality by recognizing same-sex marriages, civil unions or domestic partnerships. Six of the 10 states with the lowest LGBT populations are among the most conservative states in the country, researchers found.

California ranked 10th, with 4 percent of the population identifying as belonging to the LGBT community. On the high end of the scale, Vermont and Oregon tallied 4.9 percent, while Tennessee, Mississippi and Montana each had 2.6 percent.

Nonwhites are more likely than white segments of the U.S. population to identify as LGBT. The survey results show that 4.6 percent of African Americans identify as LGBT, along with 4 percent of Latinos and 4.3 percent of Asians, according to the study.