Mat Beren and his friends used to drive by the vast greenhouses of southern British Columbia and joke about how much weed they could grow there.

Years later, it’s no joke. The tomato and pepper plants that once filled some of those greenhouses have been replaced with a new cash crop: marijuana. Beren and other formerly illicit growers are helping cultivate it. The buyers no longer are unlawful dealers or dubious medical dispensaries; it’s the Canadian government.

On Oct. 17, Canada becomes the second and largest country with a legal national marijuana marketplace. Uruguay launched legal sales last year, after several years of planning.

It’s a profound social shift promised by Canadian Prime Minister Justin Trudeau and fueled by a desire to bring the black market into a regulated, taxed system after nearly a century of prohibition.

It also stands in contrast to the United States, where the federal government outlaws marijuana while most states allow medical or recreational use for people 21 and older. Canada’s national approach has allowed for unfettered industry banking, inter-province shipments of cannabis, online ordering, postal delivery and billions of dollars in investment; national prohibition in the U.S. has stifled greater industry expansion there. [Read more at TIME]