More than 600 gay couples rushed to town halls and courthouses across Massachusetts on Monday as the state became the first in the nation to allow same-sex marriages.

Along with the party atmosphere came moments of somber reflection and deep emotion as the day marked two sorts of milestones: the long-unthinkable leaping of a barrier in American culture and the passage of a long-awaited turning point in many lives.

It was a day in which stereotypes were not only broken but turned inside out, in which liberal lesbians expressed unstinting patriotism and conservative clergy members denounced the nation's moral and political trajectory. The United States is now one of a handful of countries -- along with Belgium, the Netherlands and Canada -- to give some gay marriages the full protection of law.

But while those on both sides of an issue that has divided the nation acknowledged the historic nature of the ceremonies, many questions about the future of same-sex marriage remain. A federal appeals court will consider a request to stop the marriages in June, and a state constitutional amendment banning gay marriage in Massachusetts could go to a referendum in November 2006.

President Bush seized the occasion to renew his call for an amendment to the U.S. Constitution defining marriage as the union of one man and one woman. And a small but vocal number of protesters in Massachusetts gave notice that their fight against the state court decision that legalized same-sex marriage here was just beginning.

-- Alan Cooperman

and Jonathan Finer

Rabbi Howard Berman signs a certificate of marriage Thursday in Boston for Matt Miller, left, and Jon Andersen.