The bulk of the marijuana consumed in the United States used to come across the border from Mexico, Canada and elsewhere. Now, more than half of it is believed to be home grown in California, where an enormous black market has emerged under the cover of the state’s medical marijuana law. With more than a third of all states now experimenting with some form of legalization and decriminalization — and several California counties attempting to openly regulate pot production — FRONTLINE and The Center for Investigative Reporting team up to investigate the country’s oldest, largest, and most wide-open marijuana market. [Explore more stories on the original website for The Pot Republic.]