The legal cannabis industry in the U.S. may grow to $50 billion in the next decade, expanding to more than eight times its current size, as lawful pot purveyors gain new customers and win over users from the illicit market, according to a new report. Legalizing recreational use in California, where the drug is already medically permitted, is on the ballot in November, and approval of that measure alone would triple the size of the nation’s current $6 billion legal industry, according to a report from 10 Cowen & Co. analysts. Legal weed would be a major opportunity for Big Tobacco, Cowen said.