Marijuana, Other Drugs, and Alcohol Use by Drivers in Washington State
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.
Voluntary and anonymous roadside data was collected in three waves: immediately before implementation of legal marijuana sales, six months after implementation, and one year after implementation. Drivers were randomly selected at six sites in Washington State. Data were collected during one 2-hour Friday daytime session (either 9:30-11:30 a.m. or 1:30-3:30 p.m.) and four 2-hour nighttime periods (10 p.m.-midnight and 1-3 a.m. on both Friday and Saturday nights). Observational and biological specimen (breath, oral fluid, and blood samples) data were requested.
This study estimated drug (and in particular, marijuana) prevalence. 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.
Data from this study is available in four formats: SAS, SPSS, Stata, and Excel; the data dictionary is compatible for all four file formats.
A weighting variable is provided for application. Its construction is described in the methodology report.