People don’t usually look forward to lining up at City Hall, but this Dec. 28 will be different.

That’s because when the clock strikes 12:01 and the calendar turns to Dec. 29, the doors of the city clerk’s office will swing open and same-sex couples from Maine will be issued marriage licenses for the first time.

These are not ordinary office hours, but this is not an ordinary occasion. These couples have been waiting all their lives for their relationships to be treated equally under the law, and telling them to wait until regular office hours on Monday, Dec. 31, is two days too long.

Congratulations to the Portland officials who recognized the historical moment and seized it. This is an enormously important day for a significant number of the city’s residents. It’s also an important moment in the history of civil rights in America.

It was just a dozen years ago when the Vermont Supreme Court gave same-sex couples the same legal rights as married couples. Since then 10 states and the District of Columbia have legalized the unions, but until this November all were done through the courts or by legislative action.

It had been a different story at the polls, however. Since the Vermont decision, 30 state votes, including Maine’s in 2009, rejected marriage equality.

But all that changed in November. Same-sex marriage was on the ballot in Maine, Maryland and Washington, and voters in all three states simultaneously said “yes” for the first time. In Minnesota, voters struck down a state constitutional amendment that would have prevented the state from passing a same-sex marriage law.

The favorable action by four states on the same day shows that this vote was no fluke. Attitudes are changing all across the country and, with the U.S. Supreme Court’s decision to take up two same-sex marriage cases next year, there’s hope this momentum could carry the change even further.

The change is happening quickly, but it is long overdue. For the people who have endured years of legal discrimination it can’t come too soon.

Portland is right to celebrate this historic moment.