There are an estimated 50 million casual marijuana user in the US and if all states and the federal government legalized weed, the industry would be worth $35-$40 billion, according to a panel of experts at NABCA's recent legal symposium. And either because the nation's feelings toward the drug are changing or because lawmakers have dollar signs in their eyes, the state dominos are beginning to fall for medical and recreational marijuana sales. Recall, recreational marijuana is now legal in Colorado, Washington State, D.C., Alaska and Oregon, and 23 states and D.C. allow medical marijuana sales.