How Has Legalization Affected Teen Marijuana Use?

"Radical" Russ 

As the data keep rolling in after the legalization of marijuana in now eight states and Washington, DC, many public policy experts are beginning to question long-held beliefs that relaxation of our country’s cannabis laws would send a message to the children that America approves of pot smoking and would thereby increase their use of marijuana. More marijuana use, in turn, would then lead to more use of other drugs, according to the so-called “gateway theory”.

One data set we can look at to evaluate how legalization has affected teen marijuana use is the annual Monitoring the Future Survey (MTF), conducted by the University of Michigan for the Substance Abuse Mental Health Services Agency (SAMHSA). Since 1975, this survey has queried 12th graders on their drug habits and perceptions (8th and 10th graders were added in 1991).

Teen Experimentation with Drugs & Alcohol

Let’s start with the drugs aside from marijuana. According to the 2016 MTF, over the past decade we have seen some of the lowest drug use figures ever recorded.


In 2016, all the teenagers surveyed reported their lowest-ever rates of having ever tried alcohol.

About 23 percent of 8th graders, 43 percent of 10th graders, and 61 percent of 12th graders reported lifetime alcohol use. The fewest-ever teens also reported getting drunk in their lifetime as well.


A similar result is found for lifetime cigarette smoking rates, which are also the lowest figures ever recorded among all teens surveyed. Additionally, the lowest ten figures ever recorded in the cigarette and alcohol categories have all been tallied since 2007, with just two out of ninety exceptions that occurred in 2006.

Turning to the illegal drugs, if marijuana is left out of the survey, then teen experimentation with all other drugs is at the lowest rate ever recorded for 10th and 12th graders, while the 8th grade lifetime use rate is the 2nd-lowest ever recorded. And like the legal drug rates, since 2007 we’ve seen nearly all the ten lowest figures ever recorded for drug experimentation by teenagers.

Teen Use of Marijuana

Could it be that marijuana legalization helped drop those drug, alcohol, and cigarette rates? Does honest and accurate discussion of adult marijuana use lead kids to trust other drug health warnings by eliminating the “reefer madness” they know is a lie?

Or did the kids just simply switch from using other drugs to using marijuana?

That doesn’t seem to be the case. Among the 8th and 10th graders, lifetime (tried it) use rates, annual use rates, and monthly use rates of marijuana have all been in decline for years now. These use rates for the past two years have been in the bottom ten ever recorded. Daily use rates among the young teens last year were also in the bottom ten, with double-digit declines over the 2000s.


Among the 12th graders, marijuana use seems to be holding steady, despite claims by prohibitionists that the 17-to-18-year-old high school seniors would have older friends in legal/medical states who would serve as straw purchasers and thereby increase access and use.

Lifetime and daily use show virtually no change over the past year and the increases in annual and monthly use are statistically insignificant (within the margin of error).

(It’s important to note that the MTF data of 1991-2016 for 8th & 10th graders means 25 entries, while the 1975-2016 data for 12th graders equates to 41 entries. Therefore, comparisons like “bottom ten” and “lowest ever” are more meaningful for the 12th grader data set.)

Teen Use of Marijuana by State

This is all interesting data at the national level. But isn’t it possible that legalization is increasing teen use at the state level, even as it decreases nationwide? Could the rest of the nation be camouflaging the effect of legalization’s message on the youth? For answers, we can turn to SAMHSA’s National Survey on Drug Use & Health (NSDUH).

At first glance, it would appear that where marijuana is legalized, more kids are toking. Indeed, 20 of the states in the top half for teen (age 12-17) marijuana use are states that now have medical or recreational marijuana legalization. In the first legal states, Colorado leads the nation in teen use monthly, with about one-in-nine teens toking, and Washington rounds out the top ten, with about one-in-eleven teens toking.


But looking at the use rates in these states is misleading without context. Nine of the top ten states for teen use have almost always been in the top ten, even before legalization or medicalization was passed. It’s not that reforming marijuana laws leads teenagers to smoke marijuana; it’s that more people using marijuana leads voters to pass reforms to marijuana laws.

A more illuminating look at the states is accomplished by looking at how the use rates have changed over time.

The state that had the greatest past-year increase in monthly teen marijuana use was Indiana – one of the six remaining states that still has absolute marijuana prohibition. Pot use among teen Hoosiers jumped from just over 6.5 percent to just over 8 percent, a relative increase of almost a quarter. South Dakota, another one of those absolute prohibition states, saw an increase of over a fifth. Kansas and West Virginia, two more of those prohibition states, had increases that made the top ten.


Meanwhile, the District of Columbia posted the 3rd-greatest relative decrease in teen marijuana smoking, with just under a sixth-fewer kids using monthly, rivaling the decline in Utah. Colorado had a double-digit decline in teen marijuana use, and Washington’s nearly 9 percent decline put all three of those jurisdictions in the top ten for marijuana use declines. Oregon was just outside at #11. Of the legal states in the data, only Alaska saw an increase in teen toking over the past year.

Teen Attitudes Toward Marijuana

One prediction by the prohibitionists about legalization does seem to have come true, however. The more we are honest with teens about marijuana’s medical benefits and the more accepting we are of regulated adult use and cultivation, the less they seem to fear and repudiate marijuana use.

But legalization hasn’t made it any easier for them to access marijuana and they are using it less often.


Among the nation’s 12th graders, their belief that someone regularly smoking marijuana is a risky behavior has fallen to its lowest level ever recorded. Fewer than one-third of teens fear regular pot smoking, down from over half just seven years ago and over three-quarters at the beginning of Bill Clinton’s presidential administration. Over the past three years, teenagers’ fear of trying or occasionally using marijuana is at levels not seen since the late 1970s.


A similar decline is found in teenagers’ disapproval of people who use marijuana. Over half of teens disapproved of trying marijuana just five years ago; that is now down to 43 percent. Occasional use was looked down on by over 60 percent just five years ago; it’s down to just half today. Regular use was frowned upon by over three-quarters; now it’s just over two-thirds.

Finally, the fear that opening adults-only marijuana stores that check I.D. would somehow increase access to marijuana for teenagers hasn’t happened. For the past forty-one years, about 80 percent of 12th graders say it would be “easy” or “fairly easy” to score some marijuana. Legalization hasn’t moved that number at all.

Summary: Marijuana Legalization Isn’t Harming Teens

It is important to note that correlation does not imply causation. Many factors contribute to whether teens choose to use drugs. However, the predictions of prohibitionists that legalization of marijuana and continued acceptance of medical use would send a message to children leading to greater use of drugs appears to be unfounded in reality. To wit:

Since the advent of the commercial medical marijuana era (2008)…

• teen alcohol, cigarette, and drug use use rates are in the bottom ten recorded rates.
• most of the states that had medical marijuana laws saw declines in teen marijuana use.
• 8th grade marijuana use declined, 10th grade use held steady, and 12th grade use increased.
• far fewer 12th graders find marijuana use risky and disapprove of it.

Since the advent of the marijuana legalization era (2012)…

• younger teen use of marijuana has declined dramatically, while oldest teen use of marijuana has remained steady.
• two-thirds of the states that had medical marijuana laws saw declines in teen marijuana use.
• 8th and 10th grade marijuana use has declined and 12th grade use has held steady.
• 12th graders’ access to marijuana hasn’t changed in any meaningful way.

Since last year, with four legal and 25 medical (+ D.C.) states…

• teen alcohol, cigarette, and drug use use rates are the lowest ever recorded (8th grade drug use = 2nd-lowest).
• two-thirds of the states that had medical marijuana laws saw declines in teen marijuana use.
• four of the five states and D.C. that had marijuana legalization saw declines in teen marijuana use (three in the top ten).
• five of the six states that maintain absolute marijuana prohibition saw increases in teen marijuana use (four in the top ten).