It is Mister Oabam, himself, who has turned the theme of the race into a referendum on rural Pennsylvania versus urbane San Francisco. Barack has made clear (at least as clear as makes it through the media fog) that the choice is between the old-school American Values of rural Pennsylvania versus the New School "American Values" of urban San Francisco.
And the effect of that choice is that many many voters, a small but significant portion of of whom skip elections, throughout the US align themselves with Pennsylvania and find San Francisco's values crazy, dangerous, even unspeakable. And they are ALL rushing the polls today.
And it is Obama, himself, who framed the election that way.
The hell of it is, those urbane San Franciscans need the Pennsylvanians a lot more than the Pennsylvanians need the San Franciscans (although the libs would never admit it). You can live without wine and cheese parties, queers, and The Vagina Monologues. Try living without steel, or 59% of electricity you use every day generated from coal.