A number of US states are considering laws to allow same-sex marriage
Gay marriage is to be permitted in the US state of Maine after a bill was passed by both houses of the state's legislature and signed by the governor.
Maine will be the fifth US state to allow gay marriage, after Connecticut, Massachusetts, Iowa and Vermont.
A number of other states, including New Hampshire and New York, are also due to consider proposals to legalise it.
Earlier this week, Washington DC's city council passed a law to recognise gay marriages performed in other states.
The issue is a controversial topic in the US, and many states have passed bills and constitutional amendments banning gay marriage.
GAY MARRIAGE IN THE US
States that allow gay marriage:
Massachusetts, Connecticut, Iowa, Vermont, Maine
States where legislation to permit gay marriage is being considered:
New Hampshire, New York, New Jersey
States that allow civil unions/domestic partnerships:
New Hampshire, New Jersey, California*, Hawaii, Oregon, Washington
States that recognise out-of-state gay marriages:
New Mexico, New York, Rhode Island
States where neither gay marriage nor any alternatives are permitted:
Alabama, Alaska, Arizona, Arkansas, Colorado, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia, Wisconsin, Wyoming
*Gay marriages conducted in California between 17 June and 4 November remain valid, according to the state's attorney general
But in the north-eastern US, momentum has begun to favour supporters of gay marriage.
Maine's lower house approved the gay marriage bill by 89 votes to 57, and the state senate voted 21-13 in favour.
Maine's governor, Democrat John Baldacci, had previously been opposed to gay marriage, but changed his mind when faced with the bill.
"I have come to believe that this is a question of fairness and of equal protection under the law, and that a civil union is not equal to civil marriage," he said in a statement.
New Hampshire's governor is set to face a similar decision shortly.
Both houses of the state's legislature have approved a bill granting gay couples the right to marry.
In California, a similar bill was passed in 2005, but was blocked by Governor Arnold Schwarzenegger.
Last year, California voters backed a constitutional amendment to ban gay marriage in a referendum, although the constitutionality of the vote is still being fought over in court.