With the expected addition of California's residents after Wednesday's Supreme Court ruling, about 30 percent of Americans will live in states offering same-sex marriage.
Now the two sides of the marriage wars are gearing up to resume the costly state-by-state battles that could, in the hopes of each, spread marriage equality to several more states in the next few years, or reveal a brick wall of traditional values that cannot be breached.
There is wide agreement from both sides on where the next battlefields will be.
Proponents of same-sex marriage were already energized by victories in six states over the last year, bringing the total number authorizing such unions to 12 states, before California. They are hoping for legislative victories this fall or next spring in Illinois and possibly New Jersey and Hawaii.
Twenty-nine states not including California have constitutional amendments defining marriage as between a man and a woman. Some advocates expect that in the November 2014 elections, Oregon and perhaps less likely, Nevada or Ohio could become the first states to undo their amendments. At the same time, a court case in New Mexico could extend marriage rights.
These strategists agree they are unlikely to win over more conservative states in the South and the West in the foreseeable future. But looking at the historical experience with issues like bans on interracial marriage, which the Supreme Court outlawed only in 1967, they feel confident that if equality spreads to more states and public attitudes continue shifting, a future Supreme Court will surely find that marriage is a right for gay men and lesbians as well as heterosexuals.
"Building a critical mass of states and a critical mass of public support that's how social movements succeed," said Evan Wolfson, founder of the group Freedom to Marry.
"We'll pursue this strategy until we finish the job," he said, "and I think it will be a matter of years, not decades."
The opponents of same-sex marriage, while unhappy that the Supreme Court struck down a key part of the Defense of Marriage Act and opened the door to gay marriage in California, are taking heart that the court did not declare same-sex marriage a constitutional right.
After a recent succession of stinging defeats in Delaware, Maryland, Maine, Minnesota, Rhode Island and Washington state after political campaigns in which they were heavily outspent the groups have also vowed to step up fundraising for advertising and mobilizing supporters.
"These court decisions could be a real boon to our fundraising," said Frank Schubert, a conservative political consultant and vice president of the National Organization for Marriage. "People tend to react when the wolf is at the door."
The conservatives also think their opponents have harvested the "low-hanging fruit" of liberal states and are nearing a limit.
"The lines are being drawn between states that stand with natural, traditional marriage and states that redefined it," said Tony Perkins, president of the Family Research Council, a conservative Christian organization.
He predicts that more Americans will turn against same-sex marriage when they see what he called its pernicious consequences introducing teachings in school that parents consider immoral, and forcing Christian business owners like florists and caterers to participate in gay marriages against their will.
Perhaps the most immediate battle will be in Illinois, a populous state with a Democratic Legislature where the Senate has already approved same-sex marriage and Gov. Pat Quinn, a Democrat, urged legislators Wednesday to "redouble our efforts to make it happen."
Many had expected the marriage bill to be adopted in May. But at the last minute, its sponsor in the House did not offer it for a vote, apparently fearing that the measure could lose and saying that some members had asked for more time.
Gay-rights groups say they think the votes are there for a win at a brief legislative session this fall. But they, and the National Organization for Marriage on the other side, are raising funds for an all-out public campaign over the next few months.
The New Jersey Legislature enacted same-sex marriage in 2012, but the measure was vetoed by Gov. Chris Christie, a Republican, and the Legislature has not taken further action. Gay-rights groups are working to gain votes, but they are also hopeful that Wednesday's Supreme Court decision to strike down parts of the Defense of Marriage Act, thus extending federal benefits to same-sex married couples, will gain them a rapid victory in state courts or the Legislature.
New Jersey, like six other states, offers legal civil unions but not marriage to gay couples.
According to a 2006 decision by the state Supreme Court, such unions must provide legal protections equal to those offered heterosexual couples. But even after Wednesday's decision, the federal government will not recognize civil unions, said Troy Stevenson, executive director of Garden State Equality thus bolstering the legal argument that unions and marriage are not equal.
On Thursday, his group and Lambda Legal said they planned to ask a state court to act on this new evidence of the inferiority of civil unions.
In broader ways, the end of the Defense of Marriage Act's ban on federal benefits for same-sex spouses will strengthen the gay-marriage cause nationally by highlighting inconsistencies and unfairness among the states, said Fred Sainz, vice president for communications with the Human Rights Campaign in Washington.
Wednesday's Supreme Court rulings, he said, will shine a light on the "two Americas: one in which legally married gay couples live and the other in which unmarried gay families live," with basic protections still out of reach.