On Tuesday, American politics became much more gay-friendly. Wisconsin voters elected a lesbian senator. Three gay men, and potentially one bisexual woman, will join the House of Representatives. And the approval of ballot initiatives means homosexuals can marry in three more states.

The gay rights movement had come to dread election days, when voters often reversed measures that legislatures and governors had backed. And opponents of same-sex marriage consistently won decisive statewide votes with far less money and manpower than its advocates.

As recently as May, North Carolina voters delivered another drubbing in a string of 30-plus statewide losses for gay-marriage activists, adding the state’s ban on same-sex marriage to its constitution. In Tuesday’s vote, those advocates welcomed a different result. “Winning for the first time at the ballot box in Maryland, Maine, Minnesota and Washington is truly historic,” said Chad Griffin, who recently took over the Human Rights Campaign (HRC), the nation’s largest gay rights organization. “You’re seeing how fair-minded Americans are, coming down on the side of full equality and inclusion in this country.”

Griffin attributed the win to new gay-straight alliances — outreach efforts with church leaders, African American activists, corporations and business leaders. Many prominent executives took the risk of alienating their customer base and ponied up chunks of their own fortunes, including the founders of Amazon and Microsoft in Washington state. The chief executive of General Mills, Ken Powell, spoke for his company against a same-sex marriage ban in the conglomerate’s home state of Minnesota.

A leading opponent to same-sex marriage discounted the victories as waged on uneven terrain. Maryland, Maine, Minnesota and Washington are “four deep-blue states,” where Democratic voters are more likely to back gay causes, said Brian Brown, president of the National Organization for Marriage (NOM).

Only four years ago, opponents of gay marriage triumphed in California’s Proposition 8 vote, which stopped a same-sex marriage law in that blue state. Brown noted that NOM achieved a decisive win there despite many newspaper editorials in favor of same-sex marriage, plus corporate behemoths such as Google and Levi’s lining up with gay rights organizations. “That’s not new” to face off against such players, Brown said. “What’s new this year is just the level of money.”

Griffin cited the $2.5 million check that Jeff Bezos, Amazon’s billionaire founder, wrote in support of Washington’s gay-marriage effort — funds that mingled with $600,000 each from Microsoft founder Bill Gates and chief executive Steve Ballmer. By Brown’s estimation, Bezos’s act of largess was a historic feat: “As far as I know, that’s the largest single donation” in the dozens of gay-marriage ballot initiatives to date.

The money spent this year was the most lopsided in favor of advocates of same-sex marriage thus far. By HRC’s tally of the Washington state race, gay rights organizations poured in nearly $12 million, while advocates of traditional marriage spent $3 million. Nationwide, HRC and NOM spent the most money, and the Catholic Church contributed large sums in its effort to prevent same-sex couples from marrying.

Earlier in the year in Maryland and Washington, legislatures passed bills to allow same-sex marriage, with the blessings, respectively, of Govs. Martin O’Malley and Chris Gregoire, both Catholic Democrats. Then traditional-marriage petitioners pushed for ballot initiatives. Maine’s vote arose after gay-marriage activists gathered enough signatures to send the same-sex marriage question directly to the voters, three years after a similar measure failed. In Minnesota, voters were asked a different question: Should the state’s existing ban on gay marriage become an amendment to the state’s constitution?

The decisive wins for same-sex marriage come shortly before what is expected to be a momentous week in the Supreme Court. Griffin said the justices could decide to hear challenges to California’s Proposition 8 and the 1996 federal Defense of Marriage Act. “We have never seen in the history of the Supreme Court where so many gay-equality cases are pending before the justices,” he said.

Many gay rights activists were optimistic that Tuesday’s sweep would inform the proceedings. “There’s no question that these votes affect the court,” said Brian Ellner, a prominent advocate for gay equality issues. “These victories make clear what the polling is already demonstrating.”

Across the street from the court, the Capitol will soon be the site of the swearing in of six openly gay lawmakers, all Democrats. Returning to the House are Reps. Jared Polis (Colo.) and David N. Cicilline (R.I.). They will be joined by Reps.-elect Mark Takano (Calif.), Sean Patrick Maloney (N.Y.) and Mark Pocan (Wis.), who won the seat now held by lesbian Sen.-elect Tammy Baldwin. In a new House district in Arizona, an openly bisexual former state lawmaker, Kyrsten Sinema, is in a race that was too close to call.

Although gay-marriage advocates poured nearly $33 million into the four state contests (and were answered with $11.3 million on the other side), the activists also supported lawmakers who had publicly called for legalizing gay marriage. With some help from gay donors, Sen. Sherrod Brown (D-Ohio) endured a difficult contest, made more complicated by the need to win over Catholic and black voters to retain his seat, when organizations in both communities had been vocal against the cause.

Gay donors turned out as well for the biggest voice of all in their cause, President Obama, who endorsed same-sex marriage in May. The president can count many HRC members among the most active fundraisers in his reelection effort. “He was there for us,” Griffin said, “and we were there for him.”

Obama campaign spokeswoman Jennifer Psaki noted the many campaign events when Obama reminded voters of his support for gay causes. “You have a sitting president out there talking with great pride that he repealed ‘don’t ask, don’t tell’ and supports how all couples should be together,” Psaki said. “It shows the tremendous amount of progress we made, and it shows the direction the country’s moving in.”