Clela Rorex, who made headlines in 1975 when, as the Boulder County clerk in Colorado, she issued a marriage license to a gay couple, one of the first to do so in the nation, died on Sunday at a hospice center in Longmont, Colorado. She was 78.

Her son Scott Poston said the cause was complications of an infection.

Colorado’s governor, Jared Polis, who is gay, was among those paying tribute to Rorex.

“So many families, including First Gentleman Marlon Reis and I, are grateful for the visionary leadership of Clela Rorex,” he wrote on Facebook, calling her a woman “ahead of her time.”

Rorex had been in the clerk’s post for only a few months when she issued the groundbreaking license, a first for Colorado and one of the first in the nation. (Two men had been issued a license earlier in Arizona, but it was quickly revoked.) She was elected the previous November.

Rorex was president of the Boulder chapter of the National Organization for Women, and her distinctive license plate “MS1” — at a time when the honorific “Ms.” was still generating controversy — attracted notice. On March 14, 1975, The Greeley Daily Tribune in Colorado ran a photograph of the back of the car, which also sported a “Yes! Equal Rights” bumper sticker.

“Boulder County Clerk Clela Rorex leaves no doubt about her sentiments on the women’s movement,” the caption read.

Poston said that when, just days later, on March 26, David McCord and David Zamora came to her seeking a marriage license, granting it was more an affirmation of her personal beliefs than an attempt to make national news.

“She didn’t do it to make a statement or create an uproar,” he said in a phone interview. “She just did it because she realized she would have an ideological contradiction if she didn’t believe in discrimination but discriminated against these men.”

She had some legal support — she had received an opinion from William C. Wise, the county’s assistant district attorney, who said that a same-sex marriage did not appear to be specifically prohibited by state law. In early April she granted a marriage license to two women, again making news.

She granted several other licenses to gay couples — “Colorado has become a mini - - - Nevada for homosexual couples,” The New York Times said at the time — before the state attorney general, J.D. MacFarlane, contradicted Wise with an opinion that marriages had to be between a man and a woman.

That led Rorex to stop issuing same-sex licenses, but her actions had already made her a hero in the gay-rights movement, as well as a target.

“I was just so inundated with mostly hate mail during that time period,” she told The Associated Press in 2004. “It was really incredible the letters I got.”

She didn’t remain clerk for long. Her son said a romance with the man who became her second husband took her to California in 1977. And, she told NPR in 2015, the year the Supreme Court ruled that gay couples had a right to marry, she probably wouldn’t have been reelected anyway given the amount of vitriol hurled at her. But she had no regrets about issuing those historic licenses.

“I just was this young woman in this place at this point in time,” she said, “and thank goodness I made that decision, because it would be so hard for me to look myself in the mirror today if I had not made the decision then.”