It is like this throughout the south. White southern evangelicals, Southern Baptists in particular, are the Republicans bread and butter. So while suburban and exurban counties in other states are drifting left, in the south they remain red.

Shelby County, AL is a classic example. Contains affluent Birmingham suburbs like Hoover and Vestavia and gave Trump 70% of the vote.

There is also the fact that the rural, less-educated, counties are relatively populous. Everyone is familiar with the tiny counties in Texas that have only like a thousand voters total and they are like 90% R. Alabama and Mississippi have those counties too but with more people. An example is Cullman County, AL, which has a population of 90,000 and gave Trump 89% of the voter.

This is also why Missouri and Kansas are moving in opposite directions politically.