ST. PAUL — With marriages to be available for Minnesota’s gay couples starting Aug. 1, Duluth residents Gary Anderson and Gary Boelhower are getting ready to do something that seemed impossible when they started dating three years ago: plan a wedding.

“The plan is to do it in August, definitely,” Boelhower said Monday, shortly after Minnesota’s Legislature took its final vote in favor of legalizing gay marriage. Democratic Gov. Mark Dayton has pledged to sign the bill, and is scheduled to do so at 5 p.m. today on the front steps of the Capitol in St. Paul.

“It means the ability to have our love and commitment recognized publicly,” Boelhower said. “To me, that’s what it’s most about.”

Minnesota is set to become the first state in the Midwest to legalize gay marriage by legislative vote, and the third nationwide in just 10 days, joining Rhode Island and Delaware. Thousands of gay marriage supporters thronging the Capitol erupted into deafening cheers after the Senate’s 37-30 vote; the House passed it last week on a 75-59 vote.

District 27 Sen. Dan Sparks, DFL-Austin, voted against the legislation.

Sparks said the vote was the most challenging decision he has had to make since being elected to office a decade ago.

“Today was more about voting on behalf of the Senate district,” said Sparks, noting that an average of about 59 percent of the district’s voters were in favor of traditional marriage in the November election.

He said the issue was a very emotional one for him — he has good friends on both side of the issue — and he has lost sleep thinking about which way he would vote.

“Members, God made gays,” Sen. Ron Latz, a Democrat from a suburb of Minneapolis, said during the Senate’s emotional four-hour debate. “And God made gays capable of loving other people. So who are we to quarrel with God’s intentions?”

The gay marriage issue shifted quickly in Minnesota, with the Legislature’s vote coming a little more than six months after voters defeated an amendment that would have banned gay marriage in the state constitution. The groups that led the campaign against the amendment swiftly turned to pushing for legalizing same-sex marriage, an effort aided when Democrats captured full control of state government in November.

Only one Republican senator, Branden Petersen of suburban Andover, voted for the bill. Three Democrats from rural districts voted against it.

Republican opponents said the bill alters a centuries-old understanding of marriage as a societal building block that benefits children.

“Forcing others to give you your rights will never end well,” said Sen. Dan Hall, a Republican and a pastor. “It won’t give you the recognition you desire.”

Hall said gay marriage supporters have told him he’s on the wrong side of history but, he said, “the truth is I’m more concerned about being on the right side of eternity.”

But supporters, too, cited religious faith and relationships with gay family members and friends as shaping their vote for the bill. Many spoke of the benefits of their own marriages.

“I could never and I would never deny the kind of recognition and all the other positive things I get out of my marriage with my husband, to anyone else,” said Sen. Vicki Jensen, a Democrat from the southern Minnesota city of Owatonna.

With passage looking inevitable Monday, vocal and visual opposition was muted. Don Lee, of Eagan, placed a tombstone on the Capitol lawn with the words “R.I.P. MARRIAGE 2013.”

“The legislation being passed today is the end of marriage as we know it in Minnesota,” Lee said. “It’s a transformation from a forward-looking sacrificial institution to one focused on adult desires.”

Supporters and opponents were close to evenly matched during the House debate, but Monday was dominated by gay marriage backers.

They taped blue and orange hearts on the Capitol steps, creating a path into the building for lawmakers with the signature colors of their movement. In the rotunda, demonstrators sang songs including “Over the Rainbow,” “Going to the Chapel” and “The Star-Spangled Banner.”

St. Paul Mayor Chris Coleman ordered the Wabasha Street Bridge near downtown festooned in rainbow-striped gay pride flags, and temporarily renamed it the “Freedom to Marry Bridge.” He also proclaimed it “Freedom to Marry Week.”

Minnesota’s most famous opponent of gay marriage also weighed in. U.S. Rep. Michele Bachmann, an ardent supporter of banning gay marriage when she served in the state Senate, released a statement expressing disappointment in a vote she said “denies religious liberty to people who believe in traditional marriage.”

Jessica Flatequal and Maria Bevacqua, a lesbian couple from Mankato who have been together for a decade, were jubilant after the vote, as supporters spilled out of the front of the Capitol.