Historically (as in past 100-150 years), the Deep South and West, though today probably only states like Mississippi, Alabama, Louisiana, etc. Virginia, North Carolina, and Georgia now have rural/urban divides that are stronger (more predictive) than, e.g., racial and class divides. Historically the West was rather homogenous politically, relatively speaking, but that's rapidly receding from memory. Though if you squint both Democratic and Republican West Coast politicians in some state (e.g. governor) and national offices (senator), but definitely not local offices, tend to still be a little more centrist than you'd expect as compared to their counterparts back east.