Hmmm, that sounds like a certain set of counties in another state.
Certainly is something I'm not certain I've heard of. Or if I have I've either ignored or forgotten.
Hellcat, a large area of the mountainous places in the south had Union sympathies.
The western counties of Virginia seceded from Virgina in June 1861 for that reason.
From the mountain areas of western Maryland and western Virginia down to the Appalachians in Georgia, the mountain people were much less 'southern' in comparison to the peoples in the valleys and piedmont regions of the same states.
I am not saying this was exactly the way it was everywhere in all the states. But everything from lifestyles to climate and economy were different in the mountain ares than in the rest of the Southern states. So those folks had less in common with the Confederacy than the other areas of the southland.
Finally, the Confederates that thought about waging a guerrilla war against the Union after Appomattox realized the mountain areas where they would need to hide out wouldn't offer them much safety or security for the same reasons.
I know there were Federal sypathizers in the Confederate states, Gettysburger. There were even Federal units organized in these areas. What I was saying I didn't know or had ignored/forgotten was that the western half of Maryland was more like the western counties of Virginia.
There were also Confederate sympathizers in the North. Not sure about any units but Ohio gave the South several generals. Some were not living there at the time of secession but still it is interesting. One of the most intresting was General Bushrod Johnson. He and his family were members of the underground railroad when he was young.