Traffic Safety Impacts of Marijuana Legalization

Recreational marijuana was legalized in Colorado and Washington in 2012. These were the first states in the US to do so. This note describes the impacts on traffic safety of marijuana legalization as observed since the year of legalization. In both states, marijuana use overall increased. In Washington, roadside surveys showing the proportion of drivers testing positive for THC (the active component of marijuana, or delta 9-tetrahydrocannabinol) indicated an increase from 14.6% to 21.4%. Washington also showed an increase in arrests and crashes involving drivers testing positive for THC. In both Colorado and Washington, fatal crashes involving marijuana increased. However, no firm conclusions are available yet for either state for possible changes in crash rates. Surveys and focus groups in both states showed that drivers believe that marijuana does not affect their driving. Many users reported driving while under the influence of marijuana use.


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  • Media Type: Digital/other
  • Features: References;
  • Pagination: 4p

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Filing Info

  • Accession Number: 01684293
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 19 2018 10:23AM