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The history of prohibition of marijuana in the United States

Leafly's guide to the history of marijuana legalization

Marijuana legalization is one the defining social movements of the late 20th and early 21st century. America went from total federal prohibition in the 1930s to 30% of the country legalizing cannabis for adult use in 2020.

Learn more about the history of marijuana legalization by browsing through the sections below.

History of prohibition of marijuana in the US

Marijuana legalization is a modern social movement that came as a reaction to marijuana prohibition—one of the main drivers of mass incarceration and systemic inequality in America.

Marijuana, better known as cannabis, was legal until the Marihuana Tax Act of 1937. Doctors prescribed pharmaceutical tinctures of cannabis to treat symptoms like migraines and PMS until the ‘40s.

However, lurid tales of reefer madness in Mexico traveled north along Associated Press news wires, and fomented state-level marijuana bans in the Southwest. Racism against Mexican-Americans and Asians—two cannabis-using immigrant minorities—resulted in state marijuana laws. Furthermore, New Deal Democrat paternalism sought to mold individual health behavior with state rules.

The American Medical Association lobbied against cannabis’ prohibition, citing the drug’s medical efficacy and low abuse potential. But the AMA was aligned with the Republican Party, who was out of power during the New Deal.

1937 Marijuana Tax Act

In 1937, Congress responded to growing state-level marijuana prohibition with the Marihuana Tax Act. At the time, the US federal government lacked the power to prohibit cannabis, so it levied a tax so punitive no one could pay it. The first marijuana arrest under the new federal law was a small-time weed dealer in Denver, CO.

Three decades of increasing drug arrests and increased marijuana use followed. Prohibition did not have a deterrence effect. Rather, prohibition creates “risk premiums” for pot activity, and thus increased profits for suppliers.

By the time of the failed Vietnam War, marijuana use had become part of a counter-cultural identity that rejected the war and associated right-wing policies.

1970 Controlled Substances Act

In 1970, Congress comprehensively updated federal drug laws with the Controlled Substances Act. The CSA placed marijuana atop a list of dangerous drugs deemed to have no medical use and wide potential for abuse. Despite decriminalization recommendations by medical experts in the Shafer Commission, President Nixon for marijuana labeled Schedule I alongside LSD and heroin.

Nixon used new drug laws to suppress political enemies on the left. Marijuana arrests exploded to over 100,000 per year in California alone—limiting employment, voting, education, and housing options for defendants. Use rates declined and then rose to new peaks in the 1990s. Meanwhile drug enforcement exploded in the Just Say No ‘80s and under the Clinton Administration.

Medical marijuana era

Marijuana legalization first took shape under medical defenses in court to possession and cultivation. In 1996, California voters led the way with Proposition 215. Stricken by the AIDS crisis, San Francisco activists ‘Brownie Mary’ Rathbun and San Francisco Cannabis Buyer’s Club owner Dennis Peron disobeyed pot law to give away cannabis to the sick and dying. Along with grower and author Ed Rosenthal, they became cause celebres that exemplified the cruelty of prohibition.

Cannabis can be an affordable, safe substance used to combat nausea, vomiting, wasting, spasticity, and a number of other AIDS and cancer-related conditions.

In 1998, Alaska, Oregon, and Washington became second, third, and fourth states to legalize medical pot with Alaska ballot Measure 8, Oregon Measure 67, and Washington Measure 692. Maine, Hawaii, Colorado, and Nevada followed after. Today over 40 US states and territories have some form of medical marijuana law.

Recreational marijuana legalization era

Medical marijuana laws and regulations offered a framework for recreational marijuana laws.

States acted like true laboratories of democracy. They learned taxing and regulating cannabis did not cause teen use to rise, decrease road safety, or other impacts. Significant tax revenues were raised. Such data allowed voters to proceed to adult-use legalization.

In 2012, Colorado and Washington became the first to legalize and license the sale of adult-use cannabis. Colorado’s extensive medical cannabis regulations were extended to include adult-use rules. By contrast, Washington medical marijuana lacked strong regulations, and adult-use ushered them in.

Oregon and Alaska followed in 2014. In 2016, California, Maine, Massachusetts, and Nevada followed, then Michigan and Vermont in 2018, and Illinois in 2019. More than 20% of the US population now lives in a legalization state.

In November 2020, four states voted to legalize cannabis for adult use: Arizona, Montana, South Dakota, and New Jersey.

Support for legalization has grown to 66% of the population, according to Pew Research; up from under 50% in the early 2000s.

Drivers of marijuana legalization

Marijuana law reform has a number of societal drivers. They include:

  • Empirical scientific fact cannabis should not be a Schedule I drug (i.e. something with a high potential for abuse, no medical use)
  • Cannabis’ use as one of humanity’s oldest botanical medicines. Its efficacy in cancer and AIDS symptom management led to the first medical cannabis legalization laws.
  • Cannabis’ low risk-profile compared to other legal and illegal substances. Cannabis has no lethal overdose, unlike alcohol or caffeine.
  • Prohibition as a driver of mass incarceration and systemic racism. Marijuana crimes drive more arrests than any other drug, and drug arrests are the number one type of arrest police make. Marijuana prohibition has saddled millions of Americans with a criminal record. The ACLU finds minorities face a far higher likelihood of arrests despite similar use rates.

Decriminalization efforts

Since the 1970s, some cities, counties, as well as states have sought to not fully legalize cannabis but decriminalize aspects of marijuana use. Ohio has a decriminalization law dating back to 1975. Many west coast cities and eventually entire western states decriminalized on the road to legalization. For example, in 2010, then California Gov. Arnold Schwarzenegger decriminalized personal possession. 

Decriminalization can mean a variety of things, from replacing pot crime with a civil fine, to making marijuana the lowest enforcement priority of a local police department (e.g. Oakland’s Measure Z).

Marijuana legalization map

States where marijuana is illegal

Below is a list of states and territories where marijuana is illegal for personal or medicinal use. Click on the name of the state or territory to navigate to more information about its cannabis prohibition.

StateLegalization statusAdult use?Medical marijuana?Decriminalized statewide?
North CarolinaIllegalNoNoYes
South CarolinaIllegalNoNoNo

Legalization guide

For a closer look at the types of legalization, check out our dedicated guides for each.

Keep up with the latest news about legalization

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