As of 8:35 a.m. Wednesday, only 48.3% of voters were in favor of the measure, which needed at least 51% to pass. However, the final vote count flipped to 50.65% yes and 49.44% no.

The results are still unofficial until they are certified, which is expected to occur on May 16. Assuming they are, Denver will be the first city in the country to decriminalize psychedelic mushrooms.

It’s important to note the bill does not legalize mushrooms, as the 2012 marijuana vote did, but largely prevents law enforcement officials from arresting or prosecuting people who had the fungi in their possession for personal use.

Psilocybin mushrooms, like THC in marijuana, have hallucinogenic effects and can send users into an altered state for up to six hours. Effects vary by person, but many researchers say they (like marijuana) can have some medicinal uses, helping people make major changes (such as quitting smoking or overcoming bouts of depression) when used in a controlled setting. Proponents say the mushrooms are safer than marijuana or alcohol, but critics of the measure (who included Denver’s mayor and district attorney Beth McCann) argued the vote was a step towards full legalization.

Proponents of the drug tout its potential medical benefits. And they’re not looking to stop with Denver. Oregon, where weed is also legal, will have a measure on its statewide ballot in 2020, allowing the drug to be used at licensed facilities.

Editor’s note: This story has been updated and corrected. An earlier version, based on incomplete vote results, mistakenly reported that the measure had failed.

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