No doubt that was the case for many instances; however, I would posit that even if the US had been homogenously either black or white as a nation, in either case as a country we would still have controlled those substances. By and large, the only places that didn't control narcotics were locations with poor/weak central governments or a history of proscribed consumption (central Asia had/has a history where it's customary for older folks to consume, but it is heavily frowned upon for non older people to consume.)