The United States became the fourth nation to allow same-sex couples to get married May 17 when a Massachusetts Supreme Judicial Court ruling from last November took effect.

Cambridge City Hall began handing out marriage licenses at 12:01 a.m. as some 10,000 gay and lesbians rallied outside.

Marcia Hams and Susan Shepherd received the first license.

“I feel overwhelmed,” Hams told reporters. “I feel ready to collapse. I’m shaking so much, I’m really ready to faint.”

Shepherd added: “There’s some kid somewhere that’s watching this and it’s going to change his whole life. ... This is about so much more than us. But it’s about us, too.”

Weddings began around the state several hours later when other government offices opened and judges began granting waivers of Massachusetts’ mandatory three-day waiting period between the issuance of a license and the marriage ceremony.

Gov. Mitt Romney has said same-sex couples from other states cannot get married in Massachusetts unless their home state recognizes gay marriages or the couple is planning to move to Massachusetts. He cites a 1913 state law that was designed to appease states that banned interracial marriage after Massachusetts allowed it.

But several Massachusetts cities have said they never applied that law to straight people and have no intention of applying it to gay people. Those cities include Somerville, Springfield, Worcester and Provincetown, which began issuing licenses to out-of-state couples immediately.

The attorneys general of Rhode Island and New York announced that their states likely will recognize the marriages of residents who marry in Massachusetts.

With weddings taking place across the state, it was impossible to keep a running count, but, at the least, hundreds of marriage licenses were handed out by clerks before the day’s end.

In Provincetown, the chairwoman of the city Board of Selectmen, Cheryl Andrews, married longtime partner Jennifer Germack.

Andrews called it “one of the greatest things that has ever happened to me. ... This is the most memorable day of my life,” she said.

“It’s like a madhouse here, darling,” Board of Selectmen secretary Vernon Porter told the Los Angeles Times. “Everyone’s giving flowers. It’s just gorgeous.”

In Cambridge, Marcia Kadish and Tanya McCloskey were believed to be the very first couple to tie the knot, at 9:15 a.m.

Kadish told reporters she felt “all tingly and wonderful” with “so much love ... bursting out of me.”

The seven couples who filed the lawsuit that led to the Supreme Judicial Court ruling – the case was named Goodridge v. Department of Public Health – all planned to marry Monday.

“Next to the birth of our daughter Annie, this is the happiest day of our lives,” said Julie Goodridge.

In Boston, Mayor Tom Menino escorted three of the plaintiff couples into City Hall.

“I am very proud to be mayor of the city on this particular day,” he said. “We have broken down another barrier. That is what life is all about – breaking down barriers and making this an open society for everyone to live in, to cherish each other and to have a great life.”

Earlier this year, the Massachusetts legislature narrowly passed a draft constitutional amendment that would ban same-sex marriage and establish civil unions that grant all state-level marriage rights. The amendment could not take effect until 2006 at the earliest, after being passed again by the legislature and ratified by voters.

Some observers predict that now that the weddings have begun, support for the amendment will drop off when legislators and citizens (a) realize the sky hasn’t fallen and (b) see all the happy gay couples celebrating their love.

A proposal to amend the U.S. Constitution to ban same-sex marriage nationwide is unlikely to clear the hurdles it faces – a two-thirds vote in the House of Representatives and the Senate, and ratification of three-fourth of the states, political observers believe – especially now that same-sex marriage is a reality.

Same-sex marriage also is allowed in the Netherlands (2001), Belgium (2002), and the Canadian provinces of Ontario (2003), British Columbia (2003) and Quebec (2004).

Several other nations grant some, most or all of the rights and obligations of marriage to same-sex couples under registered-partnership and civil-union laws.

President George W. Bush denounced the weddings taking place in Massachusetts.

“The sacred institution of marriage should not be redefined by a few activist judges,” he said en route to Topeka, Kan., where, ironically, he was commemorating the 50th anniversary of the Supreme Court decision that ended racial segregation in schools.

“All Americans have a right to be heard in this debate,” Bush said. “I called on the Congress to pass, and to send to the states for ratification, an amendment to our Constitution defining and protecting marriage as a union of a man and a woman as husband and wife. The need for that amendment is still urgent, and I repeat that call today.”

Gov. Romney said: “An issue as fundamental to society as the definition of marriage should be decided by the people. Until then, I intend to follow the law and expect others to do the same.”

Fred “God Hates Fags” Phelps and his family stood outside Boston City Hall with their colorful placards.

Focus on the Family’s James Dobson said: “We will look back 20, 30, 50 years from now and recall this day as the day marriage ceased to have any real meaning in our country. The documents being issued all across Massachusetts may say ‘marriage license’ at the top, but they are really death certificates for the institution.”

In general, however, antigay protest was muted if not invisible throughout much of the state, and the media focus was squarely on the beaming same-sex couples who repeatedly said they couldn’t believe this day actually had arrived.

“I never even fantasized about marriage,” Paul McMahon, 71, told Newsweek. “Going to other people’s weddings, I always thought they were so beautiful, and I never thought about having one of my own.”

McMahon and Ralph Hogdon, 69, have been together for 49 years.