Friday Fact: Marijuana Legalisation Drove a 10% Increase in Use Over 2016 Levels

A major new study has found that marijuana legalisation across the United States is directly driving a rise in adult cannabis use. Moreover, it challenges longstanding industry claims that making the drug legal has no meaningful impact on how many people use it.

Boston College’s School of Social Work published the research in January 2026. Notably, it found that recreational cannabis legalisation produced a 9.8% relative increase in use compared to 2016 levels. In other words, more people are picking up the habit in states where the drug became legal, and many of them had never used cannabis before.

What Marijuana Legalisation Research Found

The study drew on data from the Behavioural Risk Factor Surveillance System, covering 859,600 adults across 38 states between 2016 and 2023. To do this, researchers used a quasi-experimental approach to isolate the effect of marijuana legalisation from other social and demographic changes.

The findings are striking. For instance, recreational cannabis legalisation produced 44% lower odds of zero cannabis use, meaning adults in legalised states were far more likely to have tried the drug at all. Furthermore, on a simple yes or no measure, legalisation raised the likelihood of use by 0.94 percentage points, which represents that near 10% relative rise from 2016 figures.

Existing users did not consume more frequently. Instead, marijuana legalisation brought entirely new users into contact with the drug.

Who Is Starting to Use Cannabis After Legalisation?

The study reveals which groups responded most strongly to recreational cannabis legalisation. Surprisingly, adults aged 60 and over, women, White adults, and those with a college education all showed the sharpest increases. As a result, use rose by one to two percentage points among these groups, despite the fact that historically they all had lower rates of cannabis use.

In addition, legalisation normalises cannabis in communities that previously showed little interest in it. Consequently, the legal framework lowers the perceived barrier to trying the drug for the first time, rather than simply making life easier for existing users.

Marijuana Legalisation and Falling Perceptions of Risk

Beyond the numbers, the study points to a deeper cultural shift. As marijuana legalisation spread, so did the belief that cannabis is safe to use. Indeed, researchers found that legalisation across the country sharply reduced how often people perceived adverse consequences from cannabis use.

This matters because public perception of risk is one of the key factors that discourages substance use. When a drug becomes legal, it sends an implicit message that it carries no serious harm. For a substance with a growing body of evidence linking it to mental health difficulties, dependency, and other adverse outcomes, that message is genuinely dangerous.

Still, cannabis remains the most commonly used illicit drug in the United States. In 2023, 25.2% of people aged 18 to 25 reported using it in the past month. Among adults aged 26 and over, that figure stood at 15%.

The Cannabis Industry Narrative Under Scrutiny

For years, advocates of recreational cannabis legalisation, including commercial operators in the cannabis industry, have argued that legalisation does not increase use. However, this study offers robust, state-level evidence to the contrary. Using a well-regarded quasi-experimental design, researchers accounted for the many other factors that might explain rising use. Even so, they still found a significant effect tied directly to legalisation policy.

As a result, the research reinforces what many public health experts have long warned. Making a substance more accessible, more visible, and more socially acceptable tends to increase the number of people who use it. Clearly, the data now backs that up.

Why This Matters

Marijuana legalisation continues to expand across the United States. Therefore, understanding the real-world consequences of these policy decisions is essential. Above all, communities, families, and policymakers deserve to make informed choices based on evidence rather than industry assurances.

For families already navigating the realities of substance use, the numbers in this study are not abstract. A nearly 10% relative increase in cannabis use since 2016 represents millions of additional people using a drug that carries genuine risks. In particular, those risks are greatest for people with underlying mental health conditions or a vulnerability to addiction.

Ultimately, cannabis legalisation changes behaviour. How society responds to that fact is the question that matters most.

Source: thedrugreport