After cannabis became legal for recreational use in Washington state, use of weed dropped in among almost all groups of high schoolers and middle schoolers, according to a study from Washington State University.

Washington became one of the first states to approve adult-use marijuana sales, with the first dispensaries opening in 2014. Then, as now, one of the arguments against legalization was that it would lead to increased use by teenagers.

The study, published in the Journal of Adolescent Health, found just the opposite happened with most teens. Led by Washington State University College of Nursing Assistant Professor Janessa Graves, the study found only one group of teens increased marijuana use: 12th graders who work.

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