The Bad Stripe is a section of the US that runs from extreme southwest Pennsylania along the Appalachians, turns west and decreases in intensity through western Kentucky and Tennessee, and extends through Arkansas and into eastern Oklahoma. As noted before, it consistently shows lower values for happiness and human development indices. For US demographics and geography buffs: it's not the Black Belt, which abuts it further southeast and closer to the coast. It is clearly, however, a cultural boundary zone between north and south - basically, from the southern shore of the Ohio River to the Deep South - and the part that extends west of the Mississippi may be a result of having been settled by Appalachians, since Americans have tended to in-migrate east-to-west. But the reasons for the Strip and whether it really has resulted from the same factors remains unclear.
Below are two maps from the several earlier articles showing the frequently re-emerging Bad Stripe: increased voting GOP for president in 2008 (bright red is 15% or more increase since 2004), and self-reported by congressional district, also 2008.
So it was with great interest that I read this Medium article ("The Origin of Populist Surges Everywhere", there's another more-intense-Republican-voting map, as well as these two: death by overdose (mostly opioids, i.e. pain meds) on top, and firearm suicides on the bottom - "diseases of despair", as the author calls them.