Country noir isn’t quite regional. Or, rather, it is regional in that it is a subgenre that demands a sense of place. But it isn’t tied to any particular region. It does even really need to be set in the country. You could (and someone really should) write an excellent country noir set in the former hillbilly enclave in Uptown Chicago. That being said, the western half of North Carolina has provided the setting for a truly disproportionate number of quality country noir tales. Ron Rash is the dean of the country noir oeuvre (fight me, Daniel Woodrell fans), but ably following in his footsteps are David Joy and Wiley Cash.
This Dark Road to Mercy is my first Wiley Cash novel (he has written three). I found it a flawed work, but a thoroughly enjoyable one nonetheless and one that shows frequent flashes of brilliance.