Al Smith was the first Roman Catholic nominee to seek the presidency (on a major party ticket anyway) and I suspect that has something to do with it but I cannot account for the wide variances among the southern states.
I would suspect that that probably had a lot to do with it, acctually. Mississippi and South Carolina both have rather large Catholic communities (compared to other southern states) and Alabama has a history of being the most anti-Catholic of the southern states (which is part of the reason that Mother Angelica chose it as the HQ for EWTN).
