The Washington State Roadside Survey presents State prevalence estimates for alcohol and other drug use among drivers, with a focus on marijuana prevalence before and after the legalization of marijuana sales for recreational use in July 2014. A positive result for a drug does not necessarily mean the driver was impaired at the time of testing, only that the drug was present in the body. Data from this study cannot be used to draw conclusions about drug-impaired driving, nor can results be generalized to other States.

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