Heroin, which was primarily an urban drug, has now been adopted as a cheap alternative to pain meds. Oxy and Meth has replaced moonshine in Appalachia as the substance of choice among the non-working class.
There has been a clamp down on paid meds. Doctors stand to lose their license if they are just prescription mills now. And, some of the pills have a gel like substance added that makes it difficult to pulverize to a powder and snort/inject to the body in the rapid manner people like to get high.
This has made heroin an attractive alternative.