The Census Bureau asks Americans about subjects as varied as race, age, annual income and even their source of home heating. But there is one glaring demographic omission: The census does not ask people about their sexual orientation. As a result, there has long been a shroud of uncertainty around the geography of gay and lesbian Americans.

A new analysis of Gallup survey data offers the most detailed estimates yet about where people who identify as gay, lesbian, bisexual or transgender live.

The Gallup analysis finds the largest concentrations in the West — and not just in the expected places like San Francisco and Portland, Ore. Among the nation’s 50 largest metropolitan areas, Denver and Salt Lake City are also in the top 10. How could Salt Lake be there, given its well-known social conservatism? It seems to be a kind of regional capital of gay life, attracting people from other parts of Utah and the Mormon West.

On the other hand, some of the East Coast places with famous gay neighborhoods, including in New York, Miami and Washington, have a smaller percentage of their population who identify as gay — roughly average for a big metropolitan area. The least gay urban areas are in the Midwest and South.