After opiates become illegal, morphine maintenance clinics emerge as a way for people to safely use free or discounted opioids in a supervised setting as part of an overdose prevention plan. This is an early example of a "harm reduction" strategy. These clinics are located in cities all over the U.S., and will last for about 20 years before being shut down. Records from these clinics show a reduction in deaths by overdose in the communities that access them.