Reagan didnt do that great in the South either, he won the South by significantly less than he did nationally and still did pretty bad in the rural south.
“But dude county level results don’t matter le state shape is painted red on le map!”
Anyone who does even a basic look at past Census records can see that throughout the South many white-majority counties voted for Carter even though Reagan won the white vote in those counties. This is especially true in Mississippi, Alabama and South Carolina.
But the margins Reagan won the white vote in the rural south was still much much less than suburban south