"Obama understands, from the inside-out, systems of oppression and what they do to people," said the Rev. Jane Spahr, a lesbian who was found guilty of violating the Presbyterian Constitution for marrying same-sex couples when it was legal in California. "There is nothing like the support of hearing this from the president, that he so fully understands what love, commitment and family mean to our community."

In West Hollywood, one of the first cities to create a domestic partner registry and one of the first to pass a resolution calling for same-sex marriage rights, crowds gathered abuzz at City Hall and in cafes, phones rang off the hook and several people said they wept with joy.

In San Francisco, where the first gay marriages in the country were performed at City Hill, changing the dynamics of the 2004 presidential campaign, Mayor Edwin M. Lee said the city was prepared to resume same-sex marriages as soon as the courts would allow it.

"As someone whose position has also evolved, I know this is an issue of equality and basic human rights," said San Diego Mayor Jerry Sanders, a Republican who risked his political career in 2007 by defying his party with his support of same-sex marriage. At the time, Sanders said he could not tell his gay daughter that she did not have the right to marry; the next year, Sanders won reelection with ease.

"Two people who love each other should be able to get married. It's really as simple as that," he said. "History will judge President Obama kindly for his decision."