Five years after Illinois began accepting applicants for its medical marijuana program, the state is on the cusp of legalizing recreational marijuana.

But the drug is still classified as a “Schedule 1” substance under federal law, which makes many banks nervous to work with companies that technically traffic in an “illegal” product.

As a result, most of the medical cannabis industry is “unbanked,” and are mostly cash-only enterprises. Illinois Treasurer Mike Frerichs warns that business model is extremely risky.