I’d put my money on Southerners, like Kentucky, West Virginia or Tennessee. A hilly terrain is hard to take. Lots of natural spring water, people already heat their homes with wood and most are experienced hunters. And they’re well armed. If I’m not mistaken, Southern states produced a higher number of serviceman - folks who already know how to fight.
These hill people are only good at smoking meth and shooting heroin. They're as dependent upon the government for the food they eat as any welfare mom in Atlanta. They won't put up much of a fight, not that anyone is going to try to invade their kudzu-devoured trailer parks.
New England produces more Navy SEALS last I saw.., and there are many backwoods types here too...
Not to mention lots of engineers and firms that design/produce war materials, NVG , thermal, firearms, and ordnance...