Colorado Governor Jared Polis on Friday signed a bill into law that prohibits therapies that attempt to alter the sexual orientation or gender identity of lesbian, gay, bisexual and transgender youth, making Colorado the 18th state with such a law.

Such therapies go by names such as “conversion therapy,” “reparative therapy,” “sexual orientation change efforts” or “ex-gay therapy.”

Polis, the nation's first openly gay elected governor, also signed legislation that streamlines the process for transgender individuals to change their gender marker on their birth certificates.

Polis said that the legislation shows the progress Colorado has made since it enacted Amendment 2, the constitutional amendment approved by voters in 1992 that prohibited protected status based on sexual orientation. The Supreme Court in a landmark 6-3 decision in Romer v. Evans struck down the law as unconstitutional.

“In just 27 years, we’ve had a remarkable transformation from when we were derogatorily called the ‘hate states’ to a place where the rights of all Coloradans are respected, where we have a strong LGBTQ caucus in our state legislature, where we move forward with valued contributions that every Coloradan makes regardless of their race, regardless of their gender, regardless of their orientation, regardless of their gender identity,” Polis told a group of LGBT supporters.

The Human Rights Campaign (HRC), the nation's largest LGBT rights advocate, cheered the news, calling Friday “a great day for progress.”

“Today, we witnessed the nation’s first openly gay man elected governor, Gov. Jared Polis, sign into law two pro-equality pieces of legislation, including a bill that protects LGBTQ youth in the state from the dangerous, debunked practice of so-called ‘conversion therapy,’” HRC President Chad Griffin said in a statement. “Governor Polis has been a trailblazing champion for LGBTQ rights and representation, both in Colorado and for LGBTQ people across the nation. While there is much work to be done to ensure that all of us are treated equally under the law, this is a great day for progress – for Colorado and for our community.”

Similar laws have been enacted in 17 states plus the District of Columbia, including California, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Massachusetts, New Jersey, New Hampshire, New Mexico, New York, Nevada, Oregon, Rhode Island, Vermont. Maine's law was signed by Governor Janet Mills on Wednesday.

(Related: Puerto Rico governor signs order banning “ex-gay” therapy.)