It was a full-scale party on the South Lawn of the White House as President Joe Biden signed the Marriage Protection Act into law.
“Today is a good day,” the President exclaimed from the podium.
“Marriage is a simple proposition: who do you love, and will you be loyal to the person you love?”
Tuesday’s ceremony marks another chapter in Mr Biden’s legacy on gay rights. As vice president, he is believed to have been partly responsible for persuading then-president Barack Obama to formally back marriage equality.
Performances by singers Cyndi Lauper and Sam Smith, dancing and a lot of hugging added to the exorbitant mood.
Lauper, a long-time advocate for gay rights, exclaimed “power to the people” before launching into her classic hit True Colours.
Members of Congress from both parties were in attendance, along with first lady Jill Biden, Vice President Kamala Harris and her husband Doug Emhoff.
“For once, our families, mine and a lot of my friends — and people you know, sometimes your neighbours — we can rest easy tonight, because our families are validated,” Ms Harris said at the White House briefing room before the ceremony.
A jubilated Senate Majority Leader Chuck Schumer kicked off the ceremony with House Speaker Nancy Pelosi.
Mr Schumer noted that he was wearing the same tie he wore to his daughter’s wedding ceremony to her wife — “one of the happiest days of my life”. His daughter and her wife are expecting their first child in the spring.
Other featured guests included owner of Club Q, the nightclub in Colorado where five people were killed in a shooting last month, and two survivors of the attack.
The new law is intended to safeguard gay marriage if the US Supreme Court ever reverses Obergefell v Hodges, which legalised same-sex unions nationwide in 2015.
The new law also protects Loving v Virginia, the 1967 decision that struck down laws in 16 states making interracial marriage illegal.
“Congress has restored a measure of security to millions of marriages and families,” Mr Biden said in a statement when the legislation passed last week.
“They have also provided hope and dignity to millions of young people across this country who can grow up knowing that their government will recognise and respect the families they build.”
The vast majority of Americans support codifying marriage protections: a Gallup poll from earlier this year found that 71 per cent of people believed same-sex unions should be recognised by law.
The signing of the bill marks the culmination of a months-long bipartisan effort sparked by the Supreme Court’s decision in June to overturn Roe v Wade, the 1973 ruling that made abortion available across the country.
Justice Clarence Thomas suggested he was amenable to reversing other laws, including the legalisation of gay marriage, generating fear that more civil rights could be imperilled by the court’s conservative majority.
Mr Thomas, who is in an interracial marriage, did not include Loving v Virginia with other cases he said should be reconsidered.
A majority of Republicans in Congress still voted against the legislation, but enough supported it to sidestep a filibuster in the Senate and ensure its passage.
The Associated Press contributed to this report
