Supporters of gay rights have held numerous protests since the vote
Waving rainbow flags and placards, thousands marched through east Los Angeles, chanting: "Gay, straight, black, white! Marriage is an equal right!"
This was one of more than a dozen protests that have taken place in California and beyond since election day last week.
The marches have been peaceful but people are angry and their protests are growing.
Many of the signs they carried conveyed their feelings: "When do I get to vote on YOUR marriage?"; ''Protect my marriage''; ''Stop the h8 (hate)''.
"H8" is a play on 8, for Proposition 8, a proposal on last week's election ballot to re-write the state's constitution to redefine marriage as the union of a man and a woman only.
It was among a string of local ballots taking place across the country. And California voters approved the measure by a margin of around 3%.
So on the same day Americans elected Barack Obama, in California a small majority voted to ban same-sex marriage.
Tim Lykowski believes the law should not be set by the majority
Gay rights campaigners at the rallies say majority rule should not set the law.
The passage of Proposition 8 overturns a state Supreme Court ruling in May allowing gay weddings. Around 18,000 couples have had wedding ceremonies since.
Their marriages could now be challenged in court (although California's attorney-general says the state will defend them, as they were legal at the time) and no more can take place.
At their home north of Los Angeles, Robin Tyler and Diane Olson showed me their wedding photos.
There is an official video too, but there were so many TV crews present on their big day in June, it hardly mattered.
The two women held their wedding on the steps of Beverly Hills town hall, in the full glare of publicity.
Robin Tyler and Diane Olson want to defend their rights
They were the first lesbian couple to be legally married in Los Angeles. (At around the same time another lesbian couple, in their 80s, had a ceremony in San Francisco).
They told me they cried when they heard Proposition 8 had passed, but now are determined to fight for equal marriage rights for all.
Even though gay domestic partnerships are still recognised in California, campaigners say Proposition 8 sets a precedent of taking away a right (albeit one only granted in May) and amounts to discrimination.
Ms Tyler and Ms Olson have filed a lawsuit asking California's courts to overturn Proposition 8.
Forty Democratic politicians in the state have signed a petition calling for the same thing. No Republicans put their name to it, but state Governor Arnold Schwarzenegger has said he is not in favour of the measure.
Yet there are many who support Proposition 8 - an electoral majority, in fact, in California. They are led by church groups who say gay marriage goes against tradition, nature and the teachings of the Bible.
Among them, the Mormons gave millions of dollars to the "Yes on Prop 8" campaign. It was a bitter fight up to election day. More than $70m (£45m) was spent by both sides, much of it on negative, retaliatory TV ads.
There are many in California who have welcomed the ban
Since the vote, gay rights supporters have directed their anger at religious groups. Many rallies have been held outside churches and Mormon temples, including at the religion's headquarters in Salt Lake City, Utah.
The Mormon church says it took a stand on an important moral issue. Gay groups say religion should stay out of politics. But in America that is hard.
President-elect Barack Obama won the support of large numbers of religious voters. He also energised huge numbers of African-Americans to vote.
In California, they turned out for Obama, but they also voted on Proposition 8. And 70% of African-Americans voted in favour of banning gay marriage. Their votes were pivotal on the issue.
So, ironically, in this most liberal of states, many of the same people who turned out to elect America's first black president also voted against gay marriage.
Black voters on the gay marriage law
Many African-Americans voted that way for religious reasons: "It isn't Godly," one person told me. Others dispute the argument that gay marriage is a fundamental civil rights issue.
One thing is for certain: the election did not bring an end to the debate over gay marriage. Right now, it is more hotly contested than ever.
Campaigners plan to keep it in the headlines. And they plan to take their fight nationwide.
California is a state that often sets trends for the rest of the US, but could it now harbour a problem for the new president?