Talk Elections

Jefferson County,AL went for Bush both times and for Obama 2 times. Are Southern whites there defecting to the Dems around the Birmingham suburbs? One of the few Alabama counties to defect from Republican was Birmingham's Jefferson County in Alabama.

Higher black turn out perhaps?  I'm just guessing, I have no clue.

A lot of whites are moving out of Jefferson county and the black population is increasing.

IIRC, there were precincts in Birmingham to go against the marriage amendment, so some increase (more of a dead cat bounce) in whites for a Dem President is possible.

Mix of white flight to the neighbouring suburbs as well as even bigger margins amongst African-Americans.  Bush didn't win the county by much either time and both times he got over 10% of the African-American vote, whereas both Romney and McCain were in the single digits so I suspect that is where the difference occurred.  Also the growing Latino and Asian community may have made a difference of a percentage or two as Bush did much better amongst those than Romney or McCain and their numbers albeit small have grown each election.  I think the only counties really worth looking into are ones that Bush won by over 10 points and went Obama both times.  Since Bush won twice and Obama won twice its to be expected that a lot of the counties Bush narrowly won both times would narrowly go for Obama both times. 

Almost certainly white flight into counties like Shelby, St. Clair, and Blount.  Remember that this was one of the few Republican counties in the Deep South even in the days of the Solid South.  Even as Jimmy Carter was sweeping the state in 1976, Ford was carrying Jefferson county solidly. 

You also have a higher percentage of blacks voting for Obama than voted for Gore or Kerry - combined with lower white turnout both times