Same-sex marriages can begin within days in New Jersey after the state's highest court ruled unanimously last Friday to uphold an order that they must start Monday and to deny a delay that had been sought by Governor Chris Christie's administration.
The ruling puts New Jersey on the cusp of becoming the 14th state - and the third most populous among them - to allow same-sex marriage.
As of Monday, one-third of Americans will live in a place where gay marriage is legal.
"The state has advanced a number of arguments, but none of them overcome this reality: Same-sex couples who cannot marry are not treated equally under the law today," the court said in an opinion by Chief Justice Stuart Rabner. "The harm to them is real, not abstract or speculative."
A judge on a lower court had ruled last month that New Jersey must recognise same-sex marriage and set Monday as the date to allow weddings.
Christie, a Republican who is considered a possible 2016 presidential candidate, appealed the decision and asked for the start date to be put on hold while the state appeals.
A spokesman for Christie said that he will comply with the ruling, though he doesn't like it.
"While the governor firmly believes that this determination should be made by all the people of the state of New Jersey, he has instructed the Department of Health to cooperate with all municipalities in effectuating the order," spokesman Michael Drewniak said in a statement.
Same-sex marriage is being debated elsewhere.
Oregon has begun recognising same-sex weddings performed out of state, and it is likely that voters will get a chance next year to repeal the state's constitutional ban on gay marriage.
The Hawaii Legislature also soon could take up a bill to legalise same-sex unions, while a similar measure has passed the Illinois Senate but not the House. Lawsuits challenging gay marriage bans also are pending in several states, including Michigan, Pennsylvania and Virginia.