Amid cheers and tears, Gov. John Hickenlooper on Thursday signed a civil-unions bill into law, erasing a generation of anguish for supporters of gay rights in what once was dubbed “the hate state.”

“Unbelievable,” Hickenlooper said, looking at the gays and straight allies who were crammed into the History Colorado Center to watch history being made.

Sen. Pat Steadman of Denver, one of four gay Democrats who sponsored Senate Bill 11, recalled that “painful” night when voters approved Amendment 2, which prohibited laws from protecting gays from discrimination.

“I was there on election night in 1992 with many of you, and I see your faces in this room,” he said. “That was a very tragic moment, and yet it gave us so much hope and so much momentum moving forward. We didn’t take that defeat sitting down. We were in the streets, and we were in the courtrooms, and we were in the halls of the Capitol building.”

Steadman quoted from U.S. Supreme Court Justice Anthony Kennedy, who wrote the majority opinion in 1996 that overturned Amendment 2.

“He wrote, ‘A state cannot so deem a class of persons a stranger to its laws,’ ” Steadman said.

The atmosphere at the bill-signing was electric, with huge cheers when lawmakers and the governor took to the small stage. Senate Bill 11 gives same-sex couples many but not all of the rights and responsibilities of marriage. It goes into effect May 1.

“Dearly beloved,” Steadman said before the crowd erupted, forcing him to pause before he continued, “we’re going to make history.”

Steadman and another gay Denver Democrat, Rep. Mark Ferrandino, have sponsored the civil measures for three years, but the bills died in the previous two sessions when Republicans controlled the House. Last year’s bill died a dramatic death although Democrats had enough votes to get it passed through the House.

Democrats won back the House majority in November. This year, Steadman and Ferrandino were joined by two other gay sponsors: Rep. Sue Schafer, D-Wheat Ridge, and Sen. Lucia Guzman, D-Denver.

“What a great day to be a Coloradan,” Schafer said.

Ferrandino, who now is the House speaker, recognized the “courageous Republicans in the House and the Senate who were willing to stand up and do the right thing.”

The GOP senators who voted for civil unions last year, this year or both are Ellen Roberts of Durango, Jean White of Hayden and Nancy Spence of Centennial. The GOP House supporters are Reps. B.J. Nikkel of Loveland, Don Beezley of Broomfield, Cheri Gerou of Evergreen and Carole Murray of Castle Rock.

PHOTOS: Colorado Gov. Hickenlooper signs the civil unions bill

Gerou waved at Ferrandino when he called her name.

“I kept saying it wasn’t a matter of if; it was a matter of when,” Ferrandino said. “It’s an amazing day to be here.”

The speaker said the bill has always been personal but that it has ever more meaning now that he and his partner, Greg Wertsch, have a 15-month-old foster daughter.

“When I wake up and I go and take her out of her crib and see that smiling face, to know that after the governor signs (the bill) she’s going to have the protections just like every other family makes my heart warm,” Ferrandino said.

Hickenlooper, a former geologist who started Wynkoop Brewing Co. after the oil bust in the 1980s, said that in the early 1990s a gay employee was promoted to general manager. When a couple of customers asked to speak to the owner about the manager, Hickenlooper thought they were going to say what a good job the manager was doing.

“They said they weren’t going to come to our business anymore,” the governor recalled. “One of our waitresses was standing beside me, and she said, ‘You know, that’s not going to bother any of us at all.’ ”

The anecdote drew laughs, but Hickenlooper talked about how attitudes have changed over time.

“It is a moment that the whole community has waited for for so long,” the governor said.

One of his staffers tweeted: “From hate state to great state?”

But Steadman said the civil-unions bill is “admittedly imperfect.”

“It is not an extension of equal rights. It is not something that includes us fully and on equal footing with others in society,” he said. “There is still much to do.”

Full equality is marriage, Steadman, Ferrandino and others have said, but a constitutional amendment voters passed in 2006 recognizes marriage as only between a man and a woman.

Steadman deliberately chose the number of this year’s civil-unions measure: Senate Bill 11.

His partner, Dave Misner, who died last September after a brief battle with pancreatic cancer, was born on May 11. They had been together 11 years. Some of those who attended the civil-unions signing wore the same purple ribbons they wore at Misner’s funeral.

After civil unions passed this year, Steadman wrote a poem:

11 is a prime number.

Eleven is a lovely word.

It’s binary; a pair of ones.

It’s two like things, bound together,

to make a whole of ones.

Lynn Bartels: 303-954-5327, lbartels@denverpost.com or twitter.com/lynn_bartels