3. PARTY LOYALTY MATTERS
Party loyalty is as strong as ever. Despite the incessant discussion of whether Obama could appeal to white working-class Democrats, and whether McCain could rally conservative Republicans, in the end party loyalty was as high as in 2004–that is, about 90%. Obama also won the votes of 85% of white Democrats. See the exit polls here.
Thus, this is very much a partisan, not a “post-partisan” election (see also this WSJ op-ed). Whether the Obama presidency lessens partisan divisions in this country depends more on how he governs. Post-partisanship is not an inexorable outcome of this election itself.