But it has not been an easy road. What started four years ago in the city by the bay, ended with nuptials on Monday in San Francisco.
"I don't believe in discrimination, I want to end discrimination," said San Francisco Mayor Gavin Newsom on February 11, 2004.
With that, San Francisco mayor Gavin Newsom ordered city employees in 2004 to issue marriage licenses to same-sex couples, marking the first time any U.S. city had sanctioned same-sex nuptials.
The next day, Phyllis Lyon and Del Martin, long time community activists and a couple for 51 years, exchanged vows.
"Did you think that something like this was going to happen by now?" asked ABC7's Carolyn Tyler.
I never expected it to happen in our lifetime that's for sure," said Del Martin.
"I just believe the constitution as it's currently drafted - the state constitution - allows us to do this," said Newsom.
Gays and lesbians poured into San Francisco's City Hall, lining up to tie the knot.
"I called him and said honey let's go to city hall, I'll meet you in a half an hour we're going to get married," said newlywed Diaz.
But while the ceremonies were underway at San Francisco City Hall, the legal fight that would follow was already brewing.
Religious and traditional values advocates said the sanctity of marriage was being hijacked.
"The mayor has done a foolish thing. He has purposely violated the law, he has purposely assumed that he is right without going to court," said Rev. Lou Sheldon from the Traditional Values Coalition.
Opponents sued to stop the weddings and forced the city to go to court.
A month after the weddings started, they abruptly stopped. The State Supreme Court ordered the city to stop the ceremonies until they could review the case.
In the high court, attorneys for the state and traditional values groups argued to nullify the same-sex unions.
"They simply have no legal bearing under the California family code, they simply have never existed," said Associate Attorney General Timothy M. Muscat.
The Supreme Court ultimately agreed. The nearly 4,000 licenses issued were voided.
Meanwhile, miles away, Massachusetts began issuing licenses to same-sex couples. A national fire was burning over same-sex marriage.
Conservatives around the country fought to keep the definition of marriage as a union between a woman and a man.
Congress took up the issue as well, calling for a constitutional amendment banning same-sex marriage.
"It's not too much to ask that the 28th amendment be about protecting marriage and children," said Former Senator Bill Frist (R) Tennessee.
Ultimately, Congress failed to get the two-third vote needed to pass.
But the issue is widely seen as pushing conservatives to the polls in 2004, and helping re-elect President Bush to his second term. That seemingly closed the door to same-sex marriage in the United States.
"Nothing the president of the United States does will ever shut this door," said Mayor Newsom.
The city of San Francisco was pushing forward, working their way through the court system.
A coalition of couples from around the state sued for the right to marry in California. Their claim, California law banning same-sex marriage was unconstitutional.
"I have absolutely no doubt that we will take the next step on our way to equity, justice and equal protection under the law for all Californians regardless of sexual orientation," said City Attorney Dennis Herrera.
Almost four years from the date San Francisco began issuing marriage licenses, the case ended up back in the hands of the State Supreme Court. It was the final chance for both sides to make their case.
"If the reason to change the name marriage is to avoid having to allow lesbians and gay men access to that institution, it would violate equal protection," said Deputy City Attorney Therese Stewart.
"There are legitimate and even compelling reasons for this state to continue the traditional and universal understanding that marriage is a union between on man and one woman," said Matthew Staver from the Liberty Counsel.
Last month, the California Supreme Court ruled four to three that California's ban on same sex unions was in fact unconstitutional.
At the celebration that followed, the mayor behind it all, stood shoulder-to-shoulder with many of the couples who will now benefit from his actions on a February day four years ago.
"It's about human dignity, it's about civil liberties, it's about time in California," said Mayor Newsom.
The battle is certainly not over. Gays and lesbians are now fighting an initiative on the November ballot that would change the state's constitution to reserve marriage only for a man and a woman.
Written and produced by Ken Miguel.