Another question is why has the south become more conservative in the last 40 years?
The Southern Baptists arguably even endorsed the Roe. v. Wade decision when it happened. Now it seems like the anti-abortion position dominates the south at every level. Maybe the conventional view that the right alligned toward the views of the south isn't quite correct. Maybe the south has also alligned toward the views of the right.
Roe V. Wade was the bridge too far. Without it, you'd keep more of the catholic vote and at least part of white dixie voting democratic based on economics.