On the first day of 2014, Colorado became the first state to permit marijuana dispensaries to sell pot for recreational use. Across the state, celebratory stoners welcomed the New Year by lining up at licensed retailers to buy bags of (heavily taxed) artisanal marijuana, with varietal names like Pineapple Express and Alaskan Thunderbolt.

Since the first statewide medical marijuana laws went into effect in California in 1996, the number of Americans with legal access to what for many is a pleasurable drug has been steadily growing.

Twenty states and the District of Columbia now permit the sale of various forms of marijuana for medical purposes; in the past several months, the governor of New York, a state known since 1973 for its punitive drug laws, announced that he too would pursue accommodation for medical marijuana; and recreational marijuana is expected to be offered for sale in Washington State later this year.

Recently, the District of Columbia decriminalized the possession of an ounce or less of marijuana, treating it as a civil offense from now on.

In the least restrictive jurisdictions, purchasing medical marijuana requires a perfunctory visit to a “pot doc”—licensed physicians who specialize in prescribing marijuana, easily located through online and newspaper advertisements—for the diagnosis of any of dozens of conditions, including chronic pain, gastrointestinal distress, and depression, which the drug is believed to help alleviate.

Medical marijuana remains solidly in the realm of alternative medicine, and few clinical studies have been conducted to confirm specific claims.

After paying a consultation fee on the order of $100, new medical marijuana patients are issued a card that allows them to shop at a dispensary or order from delivery services that offer cultivars of the two major strains of the plant, Cannabis indica and Cannabis sativa, as well as potions, baked goods, and candies made from its extracts.

With the current state-level push toward legalization, voters seem to have found a way around the twentieth-century quest for prohibition—a prohibition that has become increasingly difficult to explain or justify.

Consider that marijuana remains on the federal government’s list of Schedule I drugs, defined as the most dangerous of the controlled substances, and is labeled as posing a severe risk of addiction, although many physicians don’t believe that to be true.

Unlike alcohol, excessive pot smoking has not been unambiguously implicated in violent behavior or poor health. As a Schedule I drug, under federal law, marijuana is considered to have no medical use, although there are thousands of patient testimonials to the contrary.

And perhaps the biggest contradiction of all is that since the century-long drive for prohibition was initiated, marijuana has become extremely popular. Every year, hundreds of thousands of unlucky citizens face criminal sanctions for getting caught with a drug that one third of all Americans—including college students, professional athletes, legions of entertainers, and the past three U.S. Presidents—have experimented with at least once. In popular culture, the drug has become accepted as harmless fun. In 2014, a talk show host can joke with a former congressman about being pot smokers on cable TV.

As Americans consider further legalizing marijuana it is worth reviewing how the use of this plant became illegal in the first place and why prohibition persists in much of the country more than a half century after its use became common.

Interestingly, while marijuana use has been an urgent topic of conversation for over a century in this country, the voices of doctors and scientists have been largely quiet. Instead, the debate has been shaped by media portrayals of drug use and reinforced by politicians and advocacy groups that supported them.

From Commonplace to Illegal

Today, in states with the most liberal marijuana laws, citizens’ access to the drug now resembles that of the nineteenth and early twentieth centuries, before the first attempts at federal regulation.

Cannabis, like opiates and cocaine, was freely available at drug stores in liquid form and as a refined product, hashish. Cannabis was also a common ingredient in turn-of-the-century patent medicines, over-the-counter concoctions brewed to proprietary formulas.

Then, as now, it was difficult to clearly distinguish between medicinal and recreational use of a product whose purpose is to make you feel good. The hashish candy advertised in an 1862 issue of Vanity Fair as a treatment for nervousness and melancholy, for example, was also “a pleasurable and harmless stimulant.” “Under its influence all classes seem to gather new inspiration and energy,” the advertisement explained.

While there were fads for cannabis across the nineteenth century, strictly recreational use was not widely known or accepted.

During this period, American druggists were familiar with hashish and other preparations of cannabis, and the marijuana plant had been widely cultivated for the hemp fiber used in rope and ships’ riggings.

But the practice of smoking marijuana leaf in cigarettes or pipes was largely unknown in the United States until it was introduced by Mexican immigrants during the first few decades of the twentieth century. That introduction, in turn, generated a reaction in the U.S., tinged perhaps with anti-Mexican xenophobia.

The first attempt at federal regulation of marijuana came in 1906, with the passage of the Pure Food and Drug Act. The act included cannabis among the various substances patent medicine companies were required to list on their labels in order that worried customers could avoid it.

Then, between 1914 and 1925, twenty-six states passed laws prohibiting the plant. The anti-marijuana laws were uncontroversial and passed, for the most part, with an absence of public outcry or even legislative debate.

Flush with success in pushing through alcohol prohibition, temperance campaigners in the 1920s began turning attention toward opiates and cocaine, which had become prohibited under increasingly strict Supreme Court interpretations of the 1914 Harrison Narcotics Act.

Former Spanish-American War hero Richmond P. Hobson, who had been the Anti-Saloon League’s best-paid public speaker, began warning of a dire threat posed by narcotics to national survival and the national character. Newspapers and magazines published melodramatic and sensational stories about the threat of narcotics addiction and the horrible plight of those caught in narcotics’ grip.

Following a Hollywood drug scandal in 1921, the newspapers published by William Randolph Hearst launched what became an annual crusade against narcotics with a hyperbolic and tear-jerking account by star reporter, “sob sister” Winifred Black, who also wrote under the name Annie Laurie.

Hearst’s efforts, timed to coordinate with Hobson’s annual Narcotic Education Week, exploited a new angle during the second half of decade: depicting marijuana as the largely unknown drug of murder, torture, and hideous cruelty (such as this example from 1927).

The fact that marijuana smoking was a habit of immigrants and the lower class clearly played a role in its prohibition, though there is little indication that Hearst was more racist than might be expected of a man of his time and station.

The association of murder, torture, and mindless violence with marijuana was not borne out by evidence or actual events but blossomed thanks to the vivid imaginations of the journalists charged with sensationalizing the tired story of drug use and addiction. Until a few decades prior, the public was acquainted with opiates from widespread medicinal use, and with cocaine from its presence in drugstore potions including Coca-Cola.

Journalists, politicians, police, and middle-class readers had no similar familiarity with marijuana, allowing it to become the vessel for their worst fears: addicting, personality-destroying, violence-causing. For the journalists in the 1920s charged with composing annual anti-narcotics jeremiads for Hearst’s famously sensational newspapers, a new “murder” drug must have seemed a gift.

Prohibition Repealed, But Not for Drugs

In the 1930s, the nation’s top anti-narcotics official took up the anti-marijuana cause.

Ironically, Harry J. Anslinger, a former assistant commissioner of the Prohibition Bureau who headed the U.S. Treasury Department’s Narcotics Bureau from 1930 to 1962, initially opposed federal legislation against marijuana because he foresaw it would be difficult for his agency to enforce.

However, Anslinger began to capitalize on fears about marijuana while pressing a public relations campaign to encourage the passage of uniform anti-narcotics legislation in all 48 states. He later lobbied in favor of the Marijuana Tax Act of 1937.

In Congressional testimony, Anslinger drew from what became known as his “gore file” of brutal murders and rapes allegedly committed by people high on pot. (That the marijuana was a causal factor for the crime was taken for granted.) “How many murders, suicides, robberies, criminal assaults, holdups, burglaries and deeds of maniacal insanity it causes each year can only be conjectured,” Anslinger wrote in a 1937 article in American Magazine title “Marijuana, Assassin of Youth.”

It was surely no coincidence that the scare movie Reefer Madness came a year earlier.

The 1937 Marijuana Tax Act, which regulated the drug by requiring dealers to pay a transfer tax, passed in the House after less than a half-hour of debate and received only cursory attention in the press. House members seem not to have known a great deal about the drug. In response to a question from another member, Speaker of the House Sam Rayburn (D-Tex.) explained that marijuana was “a narcotic of some kind,” while another Representative John D. Dingle (D-Mich.) appeared to confuse it with locoweed, a different plant.

In hearings, the only witness to speak against the bill was a representative of the American Medical Association, who congressmen accused of obstructionism and misrepresenting the AMA’s views.

Anslinger favored strict legal penalties against the use of narcotics, including marijuana, and worked behind the scenes to defund or discredit research that contradicted his views on the danger of these drugs or the effectiveness of prohibition.

When New York Mayor Fiorello LaGuardia and the New York Academy of Medicine produced a report in 1944 concluding that marijuana was only a mild intoxicant, it was pre-emptively attacked in the American Journal of Psychiatry in an article solicited by Anslinger.

Fourteen years later, Anslinger tried to prevent publication of a joint American Bar Association-American Medical Association study that suggested penalties for possession were too harsh. The report was ultimately published by the Indiana University Press after narcotics agents convinced the original sponsor to drop funding.

Through the 1950s, lawmakers and journalists seemed to have little patience or interest for fine distinctions among illegal drugs. Heroin, cocaine, or marijuana were all “dope”: dangerous, addicting, frightening, and bad.

The Kids Are Alright? Marijuana Comes to Campus

Views of drugs changed in the mid-1960s, with increasing reports about a new type of marijuana smoker: college students.

Along with uppers and downers—the amphetamine and barbiturate pills that had become ubiquitous through nearly every segment of American society—journalists found that the sons and daughters of America’s middle class were taking to marijuana.

The pronounced expansion of marijuana use among youth in the 1960s had no single cause. In the sweet-smelling haze, observers have seen mutiny against the values of the previous generation and the War in Vietnam, an admiration for the free-spirited Beats, and the freedom born from an excess of material wealth and time.

For many youth, smoking pot seemed harmless fun, perhaps just a little more fun because it was against the law. The mild pleasures of the drug itself seemed to refute the logic of the laws against it.

By 1965, the epidemic of drugs on campus occupied the front pages of newspapers, but neither journalists nor legislators had any enthusiasm for locking up America’s best and brightest for what increasingly seemed like a trivial offense.

By the 1960s, even Anslinger conceded the criminal penalties then in force for youthful marijuana use were too severe. In 1967, not only hippie activists but the solidly mainstream voices of Life, Newsweek, and Look magazines questioned why the plant was illegal at all.

Meanwhile, the number of state-level marijuana arrests increased tenfold between 1965 and 1970.