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Legalization Leads to Increased Marijuana Use, 
But Evidence of "Gateway Drug" Lacking

Marijuana legalization is a growing trend among American state governments. Advocates of marijuana legalization argue that the drug is a good alternative for pain relief. Additionally, marijuana tax revenue can add to state economies. For instance, Colorado raised $247 million and Washington raised $319 million from taxes and fees related to marijuana in 2017. 

Opponents of marijuana legalization often cite the "gateway drug" theory. First popularized in the 1980s, the gateway drug theory proposes that use of "soft" drugs like marijuana increases the risk of using more harmful substances, such as cocaine and opioids.

This report looks at drug use trends following legalization in Washington, Oregon, Alaska, and Colorado. These four states all legalized marijuana from 2012 to 2014, so several years of data are available from the Substance Abuse and Mental Health Services Administration (SAMHSA).  Additionally, education and employment trends are included from other civic data sources.

The U.S. national average is provided as a dotted baseline on each chart. Readers of this report can hover over any trend lines to see the data points.

Recreational marijuana is legal in nine states. The years when states passed legislation allowing recreational marijuana are shown on this map. This report focuses on the first four states to legalize recreational marijuana since they have several years of trend data. 

Marijuana use increased after state legalization. 

This chart, based on data from the SAMHSA survey, suggests that use of marijuana has increased in Oregon, Alaska, and Colorado, beginning in the year that the ballot measures passed, though slightly before the legalization took effect. The trend in Washington, by contrast, was not as noticeable.  

Marijuana use in Colorado and Oregon continued an upward trend in 2016. However, the marijuana use trend appeared to have plateaued in Alaska and Washington by 2016.

Binge drinking rates are similar to national average. 

Binge drinking among individuals 12 years and older has been inching up nationally between 2011 and 2016. 

The four states with legal marijuana had similar trajectories, with rates close to the national average.

Tobacco use is steadily declining across the United States.

Perhaps due to consistent public health marketing, tobacco use is in steady decline across the U.S. Similarly, Colorado, Washington, and Oregon experienced declines. Tobacco use in Alaska remained above the national rate, but also experienced a small decline. 

Nationally, the biggest declines in tobacco use are among 12 to 25 year olds. For 12-17 year olds tobacco use went down by the most of any age group. 10.34 percent in 2011 to 5.66 in 2016. Among 18-25 year olds, tobacco use decreased from 40.17 percent in 2011 to 31.48 percent in 2016. The percent of tobacco use among people 26 and older remained around 25 percent between 2011 and 2016. 

The decrease in tobacco use among 12 to 25 year olds has come about with the increasing number of anti-tobacco public health campaigns. States where marijuana is legal could use a similar tactic to prevent underage marijuana use. 

Cocaine use hovers between 2% to 3%.

Cocaine use remained relatively low in the U.S. between 2011 and 2016. Similarly, the use of cocaine continued to fluctuate between 2% and 3% from 2011 to 2016 for the four states with legal marijuana. 

The number of survey respondents who used cocaine is much smaller than other substances. (Note the high margins of error for this data.)

Opioid deaths increased across the United States, but Colorado, Washington, and Oregon are below the national average.

Deaths from opioids, including the illegal drug heroin, are spiking around the United States. While the four states with legal marijuana have not escaped this trend, these states have not suffered the skyrocketing mortality rates that have afflicted other regions of the country. Opioid overdose death rates in Colorado, Washington, and Oregon remained below the national average. 

Note: The CDC does not report death counts fewer than 10 to prevent individuals from being identified in small datasets, and also suppresses rate measures with small amounts of data. States with "no data" may not necessarily have zero deaths.

Education and Employment in States with Legal Marijuana

While it is too soon to tell if marijuana legalization has an effect on education and employment, we can look at the available data trends to get a sense of where these states stand today. Among these four states, education levels have remained stable and at a high level between 2011 and 2016. Colorado, the first state to legalize marijuana, has 34.3% of residents with a college degree or higher, the second highest percentage of any state.

Nationally, unemployment rates have decreased significantly between 2011 to 2018. The four states with legal marijuana also experienced a decline. Unemployment in Colorado, Washington, and Oregon all decreased at least 50%. Alaska experienced less of a decline in unemployment. 

Increased marijuana use fails to show connection to other substance use trends. 

Since legalizing marijuana, Colorado, Washington, Oregon, and Alaska all had a significant increase in marijuana use. However, these states did not experience similar trends for more addictive substances like alcohol, tobacco, cocaine, and heroin.

Marijuana legalization does present the need for new health education strategies to discourage drug abuse, especially for minors. Health educators would benefit from studying tobacco prevention education, which has contributed to a steady decline of tobacco use among younger Americans. 

Data Sources

State-level survey data for marijuana, tobacco, and alcohol use is from the Substance Abuse and Mental Health Services Administration’s (SAHMSA) National Survey on Drug Use and Health. Heroin death data is from CDC Wonder, published by the Centers for Disease Control and Prevention (CDC). State education data is from CDC’s Behavioral Risk Factor Surveillance System (BRFSS). State unemployment data is from Bureau of Labor Statistics (BLS).

More Information

• Revenue data for Colorado is from the state's Department of Revenue. For Washington, the data was taken from the state's Liquor and Cannabis Board's Annual Report

• The gateway drug theory remains controversial. This New York Times article provides an overview of the topic. 

• Campaigns to urge smokers to quit smoking have coincided with a steady decrease in smoking rates. For more details on such campaigns, see the CDC's website on the topic