Are Marijuana and Alcohol Substitutes?
Evidence from Neighboring Jurisdictions

November 22, 2019

Project Summary

Are alcohol and marijuana substitutes? For years, there has been extensive academic debate in the literature of medicine, public policy, and economics on the relationship between the two substances. The recent legalization of marijuana by several states provides new opportunities to study the relationship between marijuana and alcohol and the public health effects of legalization in neighboring states. This research examines the effects of Washington’s legalization of marijuana on alcohol consumption in neighboring Idaho.

Legalization in Washington spurred interest in marijuana dispensaries in Idaho
Using data from Google searches, Dr. Hansen identifies a significant increase in the number of web searches for dispensaries by individuals in Idaho after the legalization. This demonstrates an increased interest in marijuana products in Washington’s neighboring state.

Legalization in Washington reduced alcohol-related car crashes in Idaho
Using data on vehicle miles traveled and car crashes in Idaho, Dr. Hansen finds that the number of crashes involving alcohol decreased by 18 percent after the legalization of marijuana in Washington. This finding fades out for Idaho counties as the distance from Washington increases and provides evidence of consumers substituting marijuana for alcohol.

  • For Idaho counties that directly border Washington, the legalization of marijuana reduced car crashes involving alcohol by 21%.
  • For Idaho counties one hour away from Washington, the legalization of marijuana reduced car crashes involving alcohol by 18%.
  • For Idaho counties three hours away from Washington, the legalization of marijuana reduced car crashes involving alcohol by 10%.
  • For Idaho counties six hours away from Washington, the legalization of marijuana was not associated with a reduction in car crashes involving alcohol.

Dr. Hansen’s research suggests that marijuana and alcohol are substitutes. As marijuana becomes easier for consumers to access, individuals, drink less, as seen in fewer alcohol-related car crashes in Idaho. Policymakers should consider that there are trade-offs involved in setting drug and alcohol policies that influence public safety and the prevalence of dangerous driving.

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