Portland City Hall opened at midnight to issue the first marriage licenses under the new law. There were free carnation boutonnieres, and a jazz trio played.
Voters approved gay marriage in November, making Maine and two other states the first to do so by popular vote. The law is already in effect in Washington state; Maryland's takes effect on Tuesday, the first day of 2013.
Gay marriage was already legal in New York, Connecticut, Iowa, Massachusetts, New Hampshire, Vermont and the District of Columbia, but those laws were either enacted by lawmakers or through court rulings.
Kast and Bartlett were among about a dozen couples waiting in line at Portland City Hall. With their four daughters home for the holidays, the couple decided they would wed on the spot after getting their marriage license. They didn't see the need for another big ceremony.
"This is putting a period on an important sentence for us," said Kast, 52, who has been with Bartlett, 42, for more than six years. "We're going to finish it, and put it behind us."
The Maine Legislature had once approved same-sex marriage, but it was overturned by a statewide referendum three years ago, crushing couples who had already made wedding plans. Gay marriage supporters collected signatures to put it on the ballot again, and this time it was easily approved.
Gov. Paul LePage signed off on the certified election results on Nov. 29, so the new law was to go into effect 30 days from that date. In addition to gay marriage becoming legal, same-sex marriages in other states will now be recognized by the state of Maine.
Nobody knew exactly how many couples would be rushing to get their marriage licenses early Saturday. Falmouth joined Portland in opening at midnight. A handful of other communities including Bangor, Brunswick and Augusta planned to hold special Saturday hours.
Suzanne Blackburn and Joanie Kunian, of Portland, were among those in line to get their license at midnight, but they didn't plan to wed immediately. One of their grandchildren wanted them to get married on Valentine's Day.
"I don't think that we dared to dream too big until we had the governor's signature," Blackburn said. "That's why it's so important, because it feels real."