Cannabis has been used by humans for at least 5,000 years. It has been illegal in the United States for less than 90. Understanding how we got from millennia of widespread use to a century of criminalization — and now back toward legalization — requires tracing a timeline that involves racism, political opportunism, medical science, grassroots activism, and the slow grinding machinery of democratic reform.
This is that timeline. Not the sanitized version. The complete one.
Ancient and Pre-Colonial Use (Before 1600)
Circa 3000 BCE: The earliest written reference to cannabis as medicine appears in the Chinese pharmacopoeia attributed to Emperor Shen Nung, recommending it for rheumatism, malaria, and absent-mindedness.
Circa 2000-1400 BCE: Cannabis use spreads through Central Asia. The Scythians burn cannabis seeds in enclosed tents for ritual intoxication, documented by Herodotus centuries later.
Circa 1000 BCE-200 CE: Cannabis is referenced in Indian Ayurvedic texts as a sacred plant. Bhang — a cannabis-infused drink — becomes part of Hindu religious practice. Ancient Egyptian, Greek, and Roman medical texts reference cannabis preparations for pain, inflammation, and earaches.
500-1500 CE: Cannabis cultivation and use spreads throughout the Islamic world, Africa, and Southeast Asia. Islamic physicians document sophisticated cannabis preparations for pain management and anesthesia.
Colonial America Through the 19th Century (1600-1899)
1606-1632: French and British colonies begin cultivating hemp — cannabis sativa grown for fiber, not intoxication. The Virginia Assembly passes legislation in 1619 requiring every farmer to grow hemp. It is a strategic crop for rope, sails, and textiles.
1753: Carl Linnaeus classifies Cannabis sativa. The distinction between hemp and drug varieties is not yet formally made.
1839: Irish physician William Brooke O’Shaughnessy publishes groundbreaking research on cannabis therapeutics based on his observations in India. His work introduces cannabis to Western medicine and triggers widespread adoption.
1850: Cannabis is added to the United States Pharmacopeia, officially recognized as a legitimate medicine. Tinctures of cannabis are sold in pharmacies throughout the country for pain, nausea, and insomnia.
1890s: Cannabis tinctures are among the most commonly prescribed medicines in America. Major pharmaceutical companies including Eli Lilly, Parke-Davis, and Squibb produce and sell cannabis products.
The Road to Prohibition (1900-1937)
1906: The Pure Food and Drug Act requires labeling of patent medicines containing cannabis but does not restrict its sale or use.
1910-1920: The Mexican Revolution drives immigration to the American Southwest. Mexican immigrants bring the practice of smoking cannabis recreationally. Anti-immigrant sentiment becomes entangled with anti-cannabis sentiment. Newspapers begin using the Spanish word “marihuana” instead of the familiar “cannabis” — a deliberate rhetorical strategy to associate the drug with Mexican immigrants and make it seem foreign and threatening.
1914-1925: A wave of state-level cannabis restrictions begins, starting with border states. El Paso bans cannabis possession in 1914. California follows in 1913. By 1925, more than half of states have some form of cannabis restriction, though enforcement varies wildly.
1930: The Federal Bureau of Narcotics is created, and Harry Anslinger is appointed its first commissioner. Anslinger would become the single most influential figure in cannabis prohibition, holding the position until 1962.
1930-1937: Anslinger wages a relentless public campaign against cannabis. His testimony and public statements are explicitly racist, claiming cannabis causes Black and Mexican men to become violent, seduce white women, and lose their minds. He curates a “Gore File” of violent crimes allegedly committed under cannabis influence. Much of the evidence is fabricated or wildly distorted.
1936: The propaganda film “Reefer Madness” is released, depicting cannabis as causing insanity, violence, and death. Though intended as a serious warning, it becomes an iconic symbol of prohibition-era hysteria.
August 2, 1937: The Marihuana Tax Act passes Congress after minimal debate. It does not technically ban cannabis but imposes a prohibitive tax structure and registration requirements that make legal possession and sale functionally impossible. The American Medical Association opposes the legislation, noting that it was not consulted and that cannabis has legitimate medical applications. Anslinger dismisses the objection.
Deepening Prohibition (1938-1969)
1942: Cannabis is removed from the United States Pharmacopeia, ending its recognition as a legitimate medicine.
1944: The LaGuardia Committee Report, commissioned by New York Mayor Fiorello LaGuardia, finds that cannabis does not cause violent behavior, does not lead to addiction, and does not serve as a gateway to harder drugs. Anslinger attacks the report, threatens physicians who conduct cannabis research, and effectively suppresses further study for decades.
1951-1956: The Boggs Act (1951) and Narcotics Control Act (1956) establish harsh mandatory minimum sentences for cannabis offenses. First-offense possession carries a minimum of two to ten years in federal prison. These are among the most severe drug penalties in the Western world.
1960s: Cannabis use increases dramatically among young Americans as part of the counterculture movement. College campuses, anti-war protests, and the civil rights movement all intersect with cannabis culture. The gap between the severity of penalties and the banality of actual cannabis use becomes impossible to ignore.
The War on Drugs and Mass Incarceration (1970-1995)
1970: The Controlled Substances Act passes under President Nixon. Cannabis is placed in Schedule I — the most restrictive category, reserved for substances with “no currently accepted medical use” and “high potential for abuse.” Nixon’s own commission, the Shafer Commission, recommends decriminalization in 1972. Nixon ignores the recommendation.
1971: Nixon declares drug abuse “public enemy number one,” formally launching the War on Drugs. Decades later, Nixon domestic policy advisor John Ehrlichman would state in an interview: “The Nixon campaign in 1968, and the Nixon White House after that, had two enemies: the antiwar left and Black people. We knew we could not make it illegal to be either against the war or Black, but by getting the public to associate the hippies with marijuana and Blacks with heroin, and then criminalizing both heavily, we could disrupt those communities.”
1973-1978: Eleven states decriminalize cannabis possession. Oregon is first. The decriminalization movement appears to have momentum.
1980s: The Reagan administration reverses the decriminalization trend. Nancy Reagan’s “Just Say No” campaign reinforces zero-tolerance messaging. The Anti-Drug Abuse Act of 1986 reinstates mandatory minimums. Possession of 100 cannabis plants triggers the same five-year mandatory sentence as possession of 500 grams of powder cocaine. The crack-powder sentencing disparity receives more attention, but cannabis mandatory minimums contribute significantly to mass incarceration.
1989-1995: Annual cannabis arrests in the United States rise from roughly 400,000 to over 600,000. Black Americans are arrested at 3.7 times the rate of white Americans despite roughly equal usage rates. The racial disparity in cannabis enforcement becomes a foundational argument for the reform movement.
The Medical Cannabis Breakthrough (1996-2012)
1996: California passes Proposition 215, the Compassionate Use Act, becoming the first state to legalize medical cannabis. The vote is 55.6 percent in favor. The federal government responds with threats against physicians who recommend cannabis and raids on dispensaries.
1998-2010: Alaska, Oregon, Washington, Maine, Colorado, Hawaii, Nevada, Montana, Vermont, Rhode Island, New Mexico, Michigan, and New Jersey legalize medical cannabis through ballot initiatives or legislative action.
2009: The Obama administration issues the Ogden Memo, directing federal prosecutors to deprioritize enforcement against state-legal medical cannabis operations. It is the first formal federal accommodation of state cannabis programs.
2012: Colorado and Washington become the first states to legalize recreational cannabis for adults through ballot initiatives. Amendment 64 in Colorado passes with 55 percent support. Initiative 502 in Washington passes with 56 percent. The modern era of cannabis legalization begins.
The Legalization Wave (2013-Present)
2013: The Cole Memo establishes federal enforcement priorities that largely defer to state cannabis regulation, providing the legal breathing room the industry needs to develop.
2014: Colorado opens the first licensed recreational cannabis dispensaries on January 1. First-day sales exceed one million dollars. The predicted social catastrophe does not materialize.
2014-2018: Oregon, Alaska, Washington D.C., California, Maine, Massachusetts, Nevada, Vermont, and Michigan legalize adult-use cannabis. The pace accelerates with each election cycle.
2018: The Farm Bill legalizes hemp — cannabis with less than 0.3 percent THC — removing it from the Controlled Substances Act. Canada becomes the first G7 nation to legalize cannabis nationwide.
2019-2024: Illinois, Arizona, Montana, New Jersey, New York, Connecticut, New Mexico, Virginia, Rhode Island, Maryland, Delaware, Minnesota, Ohio, and additional states legalize adult use. By 2024, more than half of all Americans live in a state with legal recreational cannabis.
2025-2026: The federal legalization conversation intensifies. Multiple bills are introduced in Congress. The evolving landscape of employer workplace policies reflects the practical reality that cannabis is legal for most Americans even without federal action. The cannabis franchise movement signals an industry maturing into mainstream business formats.
Where We Stand in 2026
Cannabis remains a Schedule I controlled substance under federal law. This classification — alongside heroin and above methamphetamine and fentanyl — is increasingly indefensible but persists due to political inertia and bureaucratic process.
Yet the lived reality for most Americans is one of legal access. The majority of the population can purchase cannabis from a licensed retailer. Tax revenue from cannabis sales exceeds 15 billion dollars annually across all legal states. The industry employs hundreds of thousands of people.
The gap between federal law and state practice has existed for a decade now, creating a permanent state of legal contradiction that affects everything from banking to employment law to international trade.
History does not move in straight lines. Cannabis went from ubiquitous medicine to devil weed to Schedule I narcotic to the fastest-growing consumer products category in America. The prohibition era, viewed from 2026, looks increasingly like an aberration — a politically motivated deviation from thousands of years of human cannabis use that is now, slowly and unevenly, being corrected.