Cannabis (marijuana)

Cannabis (Cannabis sativa, Cannabis indica) is a cultivated annual herb. In Colorado it is best known for producing the medicinal and recreational drug “marijuana,” but it is also grown for a variety of other products, including seed oil, rope, ointments, and clothing.

The cannabis plant comes in psychoactive and non-psychoactive varieties: psychoactive cannabis is popularly known as marijuana, while non-psychoactive cannabis is known as hemp. Psychoactive cannabis came to Colorado in pharmacy products during the late nineteenth century, and later the dried flowers of the plant became a popular recreational drug smoked in cigarettes or pipes. Hemp is grown for its strong fibers and seed oil, among other products. It is unclear when hemp was introduced to Colorado, but today the crop covers nearly 6,000 acres in the state.

The Colorado legislature banned the cultivation and use of psychoactive cannabis in 1917 as part of a broader effort to curb vice in the state. The plant remained illegal until 2000, when Coloradans voted to relegalize its growth and use for medical purposes. In 2012 Colorado voters legalized nonmedical cultivation and use by those over the age of twenty-one. Hemp cultivation was banned with the passage of the federal Marihuana Tax Act of 1937, but it was relegalized in 2013 under the Colorado Industrial Hemp Act.

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Biology and Agriculture

Cannabis originated in central Asia and is one of the world’s oldest domesticated crops. Evidence of domesticated drug varieties in China date to around 2,900 BC. The plant has the largest geographic range of any crop. It can be distinguished from other weedy plants by its sets of odd-numbered, serrated leaves, which appear in various shades of green.

Cannabis plants are either male or female, but all marijuana comes from female plants. Female plants coat their developing flowers with a sticky resin that helps the plant retain moisture, blocks damaging UV rays, and catches pollen released by male plants. This resin contains dozens of compounds called cannabinoids. The principal psychoactive cannabinoid is Delta-9-tetrahydrocannabinol (THC); other cannabinoids include cannabidiol (CBD), which is non-psychoactive and can augment or temper some of THC’s effects. Each marijuana plant produces different ratios of cannabinoids that together account for the myriad effects and different “highs.”

Once pollinated, females stop producing resin and begin producing seeds. Left unpollinated, however, female plants will keep producing resin for several weeks after the flowers mature, until it completely expends itself and dies. For centuries, marijuana farmers have exploited this process by removing male plants from a crop to produce a stronger product. Today this is standard practice among growers, and the resulting product is known as sinsemilla, Spanish for “without seeds.”

Most marijuana in Colorado, legal or illegal, is grown indoors under artificial lights—an agricultural technique pioneered by American pot growers who sought to evade law enforcement in the 1980s.

Physiological Effects

When smoked or eaten, THC binds with the brain’s cannabinoid receptors and produces a variety of physical effects, including euphoria, mild sensory distortion or enhancement, dry mouth and eyes, short-term memory impairment, muscle relaxation, increased appetite, and pain relief—or some combination of the above. CBD is generally non-psychoactive and has been demonstrated to reduce inflammation, calm spastic muscles, and help protect brain cells after a serious trauma such as injury or stroke.

It is difficult to generalize about the short- and long-term effects of marijuana use. Short-term effects can be remarkably subjective while medical research on long-term effects has been inhibited by the plant’s illegal status.

Large doses of THC, such as those found in hashish and other resin concentrates as well as marijuana-infused edibles, can induce hallucinations or panic attacks. There is no risk of death by overdose. About 6 or 7 percent of users can develop dependence. Some regular users may experience minor withdrawal symptoms—including insomnia and irritability—once they stop using it, but THC does not create a physical dependence like nicotine, cocaine, or heroin.

Multiple studies on the long-term effects of marijuana use have produced no confirmed links to cancers or emphysema, but studies analyzing THC’s effect on developing mammalian brains suggest that heavy use of cannabis by children and teens carries the risk of cognitive impairment later in life. Other studies have shown a correlation between cannabis use and earlier onset of schizophrenia, though a causal link has yet to be established. Research has also demonstrated that marijuana can induce psychotic episodes in people already suffering from mental illness.

Medical Applications

Studies have provided evidence that marijuana is at least partially effective in the treatment of nausea, AIDS, cancer, epilepsy, and neuropathic pain, and other scientific evidence indicates it can help treat post-traumatic stress disorder (PTSD), glaucoma, and myriad other conditions. Some people also use cannabis to help with everyday ailments such as insomnia or anxiety. Scientific research on cannabis’s medical potential is ongoing.

History in Colorado

The American hemp industry peaked in the mid-nineteenth century and never took hold in Colorado, although some immigrants who arrived during the Colorado Gold Rush (1858–59) made the trip in wagons covered by hemp canvas. Psychoactive cannabis was likely available in some Colorado pharmacies throughout the latter part of the nineteenth century, but it was not widely cultivated in the state until after the turn of the century, when thousands of Mexican and Mexican American laborers came to work on farms, railroads, and especially in the state’s sugar beet industry.

Marijuana was not particularly popular in Mexico, but a small segment of its population—often the poorest and most transient—used it as a traditional medicine and for recreational purposes. Some of Colorado’s working-class Latinos used cannabis to help them get through a day of hard labor, while others grew and sold it to supplement meager incomes from field or railroad work.

Colorado outlawed cannabis in 1917, not because of widespread use but as part of a broader campaign to control alcohol, cocaine, and morphine. Similar campaigns were underway in multiple states during the 1910s. Colorado’s first anti-cannabis law made cultivation or use a misdemeanor punishable by no more than thirty days in jail or a fine of up to $100.

While Progressive Era campaigns against vice help explain earlier prohibitions, they were not the only reason why many Coloradans turned against cannabis in the twentieth century. By the 1920s, when anti-immigrant fever ran high across the nation and members of the Ku Klux Klan held several prominent offices in Colorado government, the white press in the state explicitly denounced marijuana as a degenerative vice of Mexican immigrants.

The federal Marihuana Tax Act of 1937 outlawed the growth and use of all cannabis, including most hemp. As with vagrancy laws, federal cannabis prohibition was more about controlling the behavior of undesirables than it was about controlling cannabis. The first two people to be charged under the new law were Denverites: twenty-three-year-old Moses Baca, a Latino man, and fifty-seven-year-old Samuel R. Caldwell, an unemployed white laborer and former bootlegger. Despite the fact that a growing number of whites were using cannabis, most of the defendants in Colorado marijuana cases during the late 1930s and 1940s had Spanish surnames.

Controlling the plant still proved difficult, as the natural spread of hempseed by birds produced patches of marijuana look-alikes in vacant lots and fields. For example, in August 1951, Denver authorities mistook a vacant lot full of wild hemp for marijuana, and GIs from the Rocky Mountain Arsenal arrived with flamethrowers to burn the weeds. The GIs torched the patch for an hour before they declared it too moist to burn.

During the 1960s and 1970s, recreational cannabis smoking became popular among young, middle-class Coloradans who identified with the American counterculture. In Denver, counterculture publications such as The Straight Creek Journal published full-page spreads on pot and ran articles covering the drug’s availability in the state, new medical research on the herb, and the US government’s support of a program that sprayed Mexican cannabis fields with Paraquat, a toxic herbicide. Patches of marijuana were a common sight on Colorado communes such as Drop City near Trinidad and Libre in the Huerfano Valley.

Anti-cannabis laws in Colorado, like elsewhere in the country, became more relaxed in light of a new group of predominantly white middle-class users. In 1973 Republican legislator Michael Strang of Carbondale introduced a bill to legalize cannabis in Colorado. The bill failed in committee, but in 1975 the legislature passed a bill that reduced the punishment for possession of up to one ounce to a $100 fine. Draconian punishments for pot possession returned in the 1980s, when anti-drug conservatives gained political momentum in the state and nationwide.

The Supreme Court ruled the Marihuana Tax Act unconstitutional in 1969, but in 1970 Congress passed the Controlled Substances Act, which arranged all illicit drugs into five categories, or schedules. Marijuana was (and remains) a Schedule I drug, a category reserved for highly addictive drugs that have no recognized therapeutic use. But since then, decades of research, including a lengthy report by the Nixon Administration’s Shafer Commission in 1972 and a comprehensive report by the National Academy of Sciences in 1982, has disproved those claims.

In 1979 the Colorado legislature approved a medical marijuana research program at the University of Colorado Health Sciences Center, but it was abandoned after the Food and Drug Administration approved Marinol, a synthetic THC pill. In 2000, after more than three decades of mounting evidence for cannabis’s medical applications, Coloradans re-legalized medical marijuana.

In November 2012, after nearly a dozen years with a thriving pot industry that made Denver a national hub for high-quality cannabis production, Colorado joined Washington as the first states to relegalize cannabis for adult, nonmedical use. The first Colorado shops opened on January 1, 2014, and the first customer was an Iraq War veteran who self-medicated with marijuana to help his PTSD. After the first month of sales, officials estimated that the legal cannabis industry collected more than $14 million in revenue, a good indication of how profitable the underground marijuana business had been over the last century.


Today cannabis plays a significant role in Colorado’s culture and economy, drawing so-called pot tourists from across the nation and world. In 2015 the state collected nearly $1 billion in revenue from legal marijuana sales, of which more than $35 million is earmarked for school construction projects. Each year on April 20 (“420” is a nickname for marijuana), thousands attend a pro-cannabis festival in Denver. As of 2015, more than 106,000 licensed Coloradans use medical cannabis to treat conditions ranging from severe pain to seizures and HIV/AIDS.

Meanwhile, hemp farmers and advocates lobby for more acreage of the industrial crop, which has applications for construction, alternative fuels, textiles, and hygiene products, among others.

In February 2015, the recreational cannabis industry sold $39.2 million worth of products. While there was some concern that legalizing cannabis would result in greater use by teens, a 2015 Healthy Kids Colorado Survey found that 63 percent of middle and high school students said they have never used marijuana.

In all, Coloradans have had more than 100 years of experience with cannabis, and that history played no small role in the strong statement that a majority of Colorado voters made in 2012 when they rejected federal prohibition. The state’s legal cannabis industry still faces many hurdles, including federal restrictions on banking, curbing the use of dangerous pesticides, tempering some of the negative effects of consumption, and lowering its carbon footprint. However, it is apparent that cannabis will remain one of Colorado’s most economically and culturally significant crops into the future.