New Jersey

[Benj]

South Jersey was not the story. The swings to Obama in South Jersey were small in Camden, Burlington, Atlantic and Ocean Counties, and Gloucester, Salem and Cape May Counties swung to Romney.

The big pro-Obama swings in New Jersey were... not where I expected them. The story of New Jersey was in urban North Jersey. Hudson County swung wildly towards Obama, by almost 5 points, and was actually more Democratic than Essex County for the first time... well, in a very long time. (Obama was 0.1% higher in Essex than in Hudson, but Romney was 0.2% higher in Essex than in Hudson.) Essex, Passaic, Union and Middlesex Counties also swung significantly towards Obama (~1.5 to 3 points), with smaller pro-Obama swings in Mercer and Bergen Counties.

As one might have predicted before the election, Romney's biggest gain was in very wealthy Hunterdon County, and he also made gains in wealthy Morris and Somerset Counties.

These data points may still change a little, though. It's not clear whether the vote-by-email votes have been counted yet, and there are probably a lot of provisional ballots from people voting at the wrong polling station as well.

[Benj]

A lot of the Obama swings are due to Sandy, no doubt. But it could be a result of NJ being younger than average and ethnically diverse. 

Now my question for someone who has never been to NJ, why is NW NJ very Republican?

This is actually an important point. The bigger swings to Obama, as I pointed out elsewhere, were not in areas heavily affected by Hurricane Sandy but rather than in minority-heavy cities and suburbs of North Jersey: Hudson, Passaic, Union and Middlesex Counties.* That suggests that at least a significant part of the swing was Obama's general, nationwide improvement among Hispanics and Asians rather than the result of Sandy, though Sandy certainly played a role as well.

*Essex County is missing from that last, but Essex is more black and less Hispanic and Asian than the those four, which may have played a role in the magnitude of the swings. It did still swing to Obama, just less.