The US Supreme Court has turned away appeals from five states seeking to prohibit same-sex marriages, paving the way for an immediate expansion of gay and lesbian unions.
The court on Monday rejected appeals to ban same-sex marriage in Virginia, Oklahoma, Utah, Wisconsin and Indiana, meaning lower-court rulings allowing gay marriage in those states remain in place.
The ruling will affect six other states - North Carolina, West Virginia, South Carolina, Wyoming, Kansas and Colorado - where appeals to strike down bans are pending.
The court's decision means the number of states with gay marriage could quickly jump from 19 to 30.
The supreme court's action means there will be no imminent national ruling but sends a strong signal that it believes gay marriage is consistent with the US constitution's guarantee of equal treatment under the law.
Chad Griffin, the president of the gay rights group Human Rights Campaign, said the ruling was a cause for celebration.
"Today is a joyous day for thousands of couples across America who will immediately feel the impact of today's Supreme Court action," he said.
It was only as recently as 2004 that Massachusetts became the first state to allow gay marriage.