SAN FRANCISCO — Dozens of gay couples planned to rush down to their county clerk's office Monday evening to be among the very first to say "I do" under the historic court ruling making California the second state to allow same-sex marriages.

The May 15 decision by the California Supreme Court was set to take effect at 5 p.m. PDT. While Mondays are not exactly a big day for weddings, at least five county clerks around the state agreed to extend their hours to issue marriage licenses, and many gay couples planned to get married on the spot.

"These are not folks who just met each other last week and said, 'Let's get married.' These are folks who have been together in some cases for decades," said Kate Kendell, executive director of the National Center for Lesbian Rights. "They are married in their hearts and minds, but they have never been able to have that experience of community and common humanity."

The really big rush to the altar in the nation's most populous state is not expected to take place until Tuesday, which is when most counties plan to start issuing marriage licenses to gay couples. Hundreds, perhaps thousands, of couples from around the country are expected to seize the opportunity to make their unions official in the eyes of the law.

Local officials will be required to issue licenses that have the words "Party A" and "Party B" where "bride" and "groom" used to be.

A conservative Christian legal group asked a state appeals court to block the weddings, but the move was given little chance of success. California's high court rejected a previous request for a postponement.

In San Francisco, where Mayor Gavin Newsom helped launch the series of lawsuits that led the court to strike down California's one-man-one-woman marriage laws, workers got ready for the crush of couples by setting up a satellite office in the lobby of City Hall.

Newsom planned to preside at the wedding of lesbian rights activists Del Martin, 87, and Phyllis Lyon, 84, the only couple scheduled to receive a marriage license in the city on Monday. As of Friday, nearly 620 couples had booked appointments to obtain licenses at San Francisco City Hall over the next 10 days.

Clerks elsewhere around the state reported nowhere near as high a demand but said they were training volunteer marriage commissioners to officiate at civil ceremonies in anticipation of a surge in business.

Unlike Massachusetts, which legalized gay marriage in 2004, California has no residency requirement for marriage licenses, and that is expected to draw a great number of out-of-state couples. The turnout could also be boosted by New York state's recent announcement that it will recognize gay marriages performed in other jurisdictions.

A UCLA study issued last week estimated that half of California's more than 100,000 same-sex couples will get married over the next three years, and an additional 68,000 out-of-state couples will travel here to exchange vows. The study estimated that over that period, gay weddings will generate some 2,200 jobs and $64 million in badly needed tax revenue for the state, which is ailing financially.

Some of those out-of-state couples are likely to demand legal recognition in their home states, setting the stage for numerous court battles.

However, some couples may wait to tie the knot because of a proposed constitutional amendment on the California ballot in November that would undo the Supreme Court ruling and ban gay marriage.

Amid the preparations, some religious leaders and conservative activists objected to the social change unfolding around them. The seven bishops of the Archdiocese of Los Angeles issued a statement Monday reiterating the Roman Catholic Church's position on same-sex marriage.

"The church cannot approve of redefining marriage, which has a unique place in God's creation, joining a man and a woman in a committed relationship," the bishops said.

Although government officials cannot legally withhold marriage licenses from same-sex couples, the clerks in comparatively conservative Kern, Calaveras and Butte counties last week stopped performing weddings altogether.

Among the reasons they cited were concerns that the increased demand would overwhelm their staffs and endanger the security of the election equipment they also oversee as part of their jobs.

Robin Tyler, 66, and Diane Olson, 54, who like Lyon and Martin were among the two dozen couples who served as plaintiffs in the litigation, also were scheduled to get married on Monday afternoon. The Los Angeles County clerk agreed to issue them a marriage license a day ahead of the general public in recognition of their role in the case.

"The word 'marriage' is important to me to this day because marriage is a universally understood word," Olson said. "Robin is a different relationship to me than any other relationship I've had in my life. She's my special person."


Associated Press writer Laura E. Davis in Los Angeles contributed to this story.