Effective Jan. 1, 2019, New York City will now allow a third gender option to be included on birth certificates in the city. Denoted simply as “X”, the option was created for gender nonconforming citizens.

New York City Mayor Bill DeBlasio signed a bill on Tuesday, calling the law “an essential example of freedom.”

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“If you’re denied the right to express yourself, you don’t have freedom. If you have to sit by the door of a classroom worried that someone is going to typify you the wrong way and deny your identity, you don’t have freedom. You don’t feel free,” DeBlasio said.

“You be you,” DeBlasio said, addressing his constituency, during the bill’s signing. “Live your truth, and know that New York City will have your back.”

New York also does away with the requirement that transgender people get a note from a medical professional in order to change their gender identity on their birth certificate. The new law allows them, instead, to “self-attest” to their gender – a change that is expected to make it easier to change other forms of ID. Residents under age 18 will need parental consent.

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Introduced by New York City Council Speaker Corey Johnson, the legislation expands on an earlier bill Johnson fought for during his first term in 2014, which eliminated the requirement that people seeking hormone therapy or gender-confirmation surgery change their gender on their birth certificate first, according to Rolling Stone.

New York, however, wasn’t the first state to enact this type of law.

Maine passed similar legislation allowing residents to identify as either male, female or “X” on driver’s licenses and ID cards. The law goes into effect next year. Washington State passed a bill allowing people to identity as “X” on their birth certificates earlier this year.

On September 1st in California, the “Gender Recognition Act” became law, allowing residents to identify as “nonbinary” on birth certificates and state identification. California elected leaders define nonbinary as defined under the bill as an “umbrella term for people with gender identities that fall somewhere outside of the traditional conceptions of strictly either female or male.”