Possession of psilocybin, the active ingredient in psychedelic mushrooms, is a felony.

"Magic" mushrooms are classified as a Schedule 1 drug, a category used for substances that don't have a medicinal benefit.

Some recent studies suggest that psilocybin could be helpful for people with anxiety, depression, and alcoholism.

In Denver, a campaign trying to decriminalize hallucinogenic mushrooms has gathered enough signatures to place a measure on the ballot for the city's municipal elections in May.

Oregon is also getting closer to decriminalizing psilocybin. Psychedelic mushrooms could become legal in the state in 2020.

Denver, Colorado could become the first US city to decriminalize psychedelic mushrooms after a campaign gathered enough signatures to put a "magic" mushrooms measure on the ballot for the municipal elections in May.

CNN reported that nearly 9,500 people signed off on advancing the measure, which needed 4,726 signatures to proceed. The Denver Elections Division, which tweeted on January 7 that it had received the petition, now needs to verify the signatures' legitimacy within 25 days.

The measure, containing language based on a 2007 effort that decriminalized recreational marijuana in Denver, would not legalize hallucinogenic mushrooms, which contain psilocybin as an active ingredient. The ordinance would, however, make the use and possession of psilocybin by people above age 21 the city's "lowest law enforcement priority," local news outlet NBC 9 reported.

Magic mushrooms are currently classified as a Schedule 1 drug, a category that the federal government uses for substances that have no medicinal benefit. Heroin and ecstasy are both considered Schedule 1 drugs.

While the Denver measure would not change the drug's classification, it would impact how city officials view psilocybin. Denver would no longer be able to prosecute cases related to psilocybin if the measure passes in May.

In addition, the ordinance would form a review panel of two city council members and other residents to examine the impacts of adopting the measure.

For Kevin Matthews, the campaign director of Denver for Psilocybin, decriminalizing psychedelic mushrooms is personal. He told NBC 9 that psilocybin has helped him with depression.

An effort to change the laws around hallucinogenic mushrooms is also underway in Oregon, but it goes a step further towards legalization. The secretary of state has approved language for a ballot initiative that could make psychedelic mushrooms legal in 2020. If the measure passes, the state would allow hallucinogenic mushrooms to be manufactured for medical use under a license.

Read more: Oregon is closer than ever to becoming the first state to legalize 'magic' mushrooms

A woman harvests magic mushrooms in a grow room at the Procare farm in Hazerswoude, central Netherlands, August 3, 2007. Peter Dejong/AP

More and more Americans are opening up to the idea of legalizing marijuana and other illegal substances, and some scientists have recently concluded that psychedelics could have positive effects.

According to recent studies, psilocybin could help reduce anxiety in people with cancer and could be used as a treatment for anxiety, depression, and alcoholism.

Researchers at Johns Hopkins University said last year that psilocybin should not be classified as a Schedule I drug. In an article published in the medical journal Neuropharmacology, they wrote that psilocybin should be categorized as a Schedule IV drug, a classification that includes prescription sleeping pills.

Five years could go by before any changes are made, however, as all substances have to undergo tests before the Food and Drug Administration make a call on reclassification.

Jeff Hunt, the vice president of public policy at Colorado Christian University, told NBC 9 that more research is needed to fully understand the long-term impact of hallucinogenic mushrooms.

"This is a psychedelic drug. This is not some supplement that you take that’s going to have some vitamins, nutritional value that adds to your life," Hunt told the news outlet. "This has a psychedelic effect to it that’s going to affect how you look at the world and how you interact with the world."

Correction (January 10, 2019): A previous version of this story misstated cocaine's classification by the US Drug Enforcement Administration. Cocaine is a Schedule 2 drug.