REHOBOTH BEACH, Del. — So much for San Francisco.

The list of top cities for same-sex couples as a portion of the population does not include that traditional gay mecca, according to new census data. In fact, the city, which ranked third in 1990 and 11th in 2000, plummeted to No. 28 in 2010. And West Hollywood, once No. 1, has dropped out of the top five.

The Census Bureau data, finalized this week and analyzed by Gary Gates, a demographer at the Williams Institute at the University of California, Los Angeles, gives the clearest picture to date of same-sex couples in America. In absolute numbers, they jumped by half in the past decade, to 901,997.

Most surprising is how far same-sex couples have dispersed, moving from traditional enclaves and safe havens into farther-flung areas of the country.

Consider, for example, the upstarts on the list: Pleasant Ridge, Mich., a suburb of Detroit; New Hope, Pa.; and this beach town in southern Delaware. All three have been popular destinations for gay people locally but had never ranked in the top 10.