Over the past few years, a growing number of Americans have voiced their support for legalizing marijuana, leading four states to legalize it for recreational and medical uses and 19 more for only medical purposes.

But does this sentiment apply to other illicit drugs? That's what Vox and Morning Consult sought to find out in a new poll of nearly 2,000 registered US voters.

The results overwhelmingly suggest that marijuana is a big outlier, and most US voters do not support decriminalizing non-marijuana drugs or legalizing them for medical or recreational purposes.

Most US voters do not want to decriminalize non-marijuana drugs

Except for marijuana, there is little support for decriminalizing drugs to remove the threat of arrest, jail time, and a criminal record for possession of small amounts of a drug.

This, to me, is the most surprising result of Vox and Morning Consult's poll. In a 2014 survey of US adults by the Pew Research Center, 67 percent of respondents said that drug policy should focus on providing treatment instead of prosecuting drug users. But that apparently does not mean that most Americans want it to be impossible for the government to prosecute certain drug users.

The poll defined decriminalization to respondents as a change that makes it so drugs carry "no arrest, prison time, or criminal record for the first-time possession of a small amount of that drug for personal use."

But the poll did not specify that a fine could be left in place under decriminalization, which could have influenced the results. (Specifying this, along with survey questions about what should be the right punishment for drug possession, would make for some interesting follow-up polling.)

Respondents were generally more supportive of decriminalization than legalization for medical or recreational uses, but still overwhelmingly opposed all of these options for non-marijuana drugs.

Demographics played a role, too. Younger, liberal, and Democratic voters generally voiced higher levels of support for decriminalization and legalization for medical and recreational purposes, but a big majority still opposed all three of these policy changes for every drug but marijuana.

Most US voters do not want to legalize non-marijuana drugs for medical purposes

When it comes to drugs and their medical uses, there are some discrepancies among what voters think, the law, and the research.

For one, cocaine and meth are already legally allowed for limited medical uses: Cocaine is an anesthetic, and meth is used to treat ADHD and obesity.

For medical hallucinogens, an early — but growing — body of research suggests that drugs like magic mushrooms (psilocybin), acid (LSD), ibogaine, and ecstasy (MDMA) could be effective in controlled medical settings for all sorts of illnesses, including anxiety, nicotine addiction, and PTSD. But this research is fairly preliminary, and voters may not know much, if anything, about it.

Still, a small fraction of Americans have tapped into at least one medical hallucinogen: ibogaine. As I previously wrote, some Americans suffering from opioid painkiller and heroin addiction have gone to Mexico to use ibogaine, which is provided in supervised settings by some clinics and resorts in the country. Patients told me that the very intense hallucinogenic experience of ibogaine helps ease their anxiety and addiction for months or more at a time.

But Americans appear to know little about ibogaine, with respondents more likely to answer "don't know" or "no opinion" to questions about legalizing or decriminalizing ibogaine compared with other drugs.

Most US voters really do not want to legalize non-marijuana drugs for recreational purposes

Given that most US voters oppose decriminalization and medical legalization for all the non-marijuana drugs we polled for, it's little surprise that respondents strongly oppose legalizing non-marijuana drugs for recreational uses.

The poll did find, however, that a majority of Americans support marijuana legalization. That's in line with other polling from Gallup and the Pew Research Center, which have found that support for legalization has grown over the years.

But if drug policy reformers want to pull back criminalization on other drugs, Vox's poll shows they still have a lot of work to do with the American public.

Morning Consult polled 1,994 registered voters between March 10 and March 13, 2016. The interviews were conducted using large, established online survey vendors and were weighted to approximate a target sample of registered voters based on age, race/ethnicity, gender, educational attainment, region, annual household income, home ownership status, and marital status. Results from the full survey have a margin of error of +/- 2 percentage points. Topline results are available here, and cross-tabulation results are available here.