Victoria Kolakowski declared victory Monday in a tightly contested race for Alameda County Superior Court, making her what is believed to be the nation's first transgender judge.

In the final, uncertified tally, Kolakowski defeated John Creighton by 51 to 48 percent, the Alameda County registrar of voters said. She received 162,082 votes to 152,546 for Creighton.

Kolakowski, 49, has 21 years of legal experience, including stints as a private attorney, corporate attorney and, currently, administrative law judge. She argued during the campaign that she would bring professional diversity to the bench, where many judges are former prosecutors.

Creighton, 58, an Alameda County deputy district attorney, countered that his background as a prosecutor made him better suited for the job.

Kolakowski said Monday that the election outcome "speaks well of our ability to look past differences and look to the things that matter: our ability and experience."

Creighton congratulated Kolakowski.

"I feel like I conducted the best campaign I could," he said. "I wish Ms. Kolakowski luck in her position."

Kolakowski transitioned from male to female in 1989 during her last year in law school and had sex reassignment surgery in 1991.

Statewide transgender-advocacy groups paid for robo calls and mailers supporting Kolakowski's candidacy and helped get out the vote for her Nov. 2.

"There's never been a transgender judge that anyone we know is aware of," said Geoff Kors, executive director of Equality California, a gay rights group that assigned volunteers to call its 32,600 Alameda County members and urge them to vote for Kolakowski.

Her election, said Kors, "shatters a glass ceiling."