Why are whites in LaSalle Parish, LA so reactionary?

[VPH]

It's in Protestant northern LA and it's adjacent to the Mississppi river valley which has a larger black population. I guess the parish is distant enough from them to attract whites who don't want to live there.

I wonder the extent to which this also helps explain counties like Glascock in Georgia, which really stands out against its neighbors. I once emailed a local professor about it and he didn't have much insight.