And such unions might soon be recognized at the other end of the country in New York, where the governor has directed state agencies to do so.

California said it chose June 17 because the state Supreme Court has until the day before to decide whether to grant a stay of its May 15 ruling legalizing gay marriage.

Gay-rights advocates and some clerks initially thought couples would be able to wed as early as Saturday, June 14. The court's decisions typically take effect 30 days after they are made.

The guidelines from Janet McKee, chief of California's office of vital records, to the state's 58 county clerks also contained copies of new marriage forms that include lines for "Party A" and "Party B" instead of bride and groom. The gender-neutral nomenclature was developed in consultation with county clerks, according to the letter.

"Effective June 17, 2008, only the enclosed new forms may be issued for the issuance of marriage licenses in California," the directive reads.

A group opposed to gay marriage has asked the court to stay its decision until after the November election, when voters are likely to face a ballot initiative that would once again define marriage as a union between a man and a woman. Passage of the initiative would overrule the Supreme Court.

Under the Supreme Court's regular rules of procedure, justices have until the end of the day June 16 to rule on the stay request, according to the memo sent by e-mail to county clerks. Lawyers involved in the marriage case have said previously the court could grant itself an extra 60 days to consider the stay.