The New Jersey switch is mainly due to the liberalization of old-line white suburbs, especially those in the northern half of the state, which have moved further socially left as social issues have become more important and the Democrat party has moved socially left along with them.
New Jersey was traditionally a Republican state and should have moved with the Republicans. The fact that they didn't attests that they opposed the dixiecrat takeover of the party and the subsequent radicalization of the GOP on social issues. Imagine you are a regular Rockefeller New Jersey Republican, then suddenly your party gets taken over by evangelicals. New Jersey hasn't become more socially liberal so much as the GOP has radicalized into social conservatism-- leaving NJ in nowhere left to go but Democrat by default.
hmmm, perhaps. I think I should have described it better as being both things happening at once, Republicans moving more socially conservative, New Jersey/NE suburbs in general moving more socially liberal.
Anyway, it's a minor point. What happened in real political terms is fairly obvious to see.
