The democrats started losing the south after the civil rights fights during the 60's when the dem. leadership sided with civil rights and against the old school democrats of the south.
As to the rest I don't know.
I think the main factor in this last election is the way the two parties interact with their members/followers. In US politics there are only 2 parties, so each party is going to have to represent a broad spectrum of voters who in other countries would have many parties to choose from.
I was on vacation durring the democratic convention, but I did listen to the republican convention. The one thing that struck me was that the republicans are good at telling their members that you don't have to agree with our whole agenda just a couple parts to be a republican. The expectation in the democratic party is for everyone to agree with all aspects of the party platform.
Right now I think there are a lot of republicans out there who don't agree with the current deficit spending and interventionist foriegn policy however they feel like they are part of the party. Next election things may change; after all this election was not a landslide.