Final Pennsylvania Polling

Quinnipiac has Clinton leading by seven, 51% to 44%. (She leads by double digits among women, by 40 points among white Catholics, and with older voters; he leads among men, younger voters and African Americans.)

Suffolk U has Clinton leading 52% to 42% with 4% undecided;

Mason-Dixon has Clinton leading by 5 points -- 48% to 43%.

ARG has Clinton leading by 13 points.

The robopollsters also agree on the fact of a Clinton lead: Strategic Vision has Clinton leading by 7 points, and PPP has Obama leading by three.

The difference in these numbers appears to correspond to the difference in how they estimate turnout among various demographic groups and in geographic regions. Obviously, if turnout in Philadelphia is especially high, Obama will do better than expected; if Clinton's organization in the "T" is solid, Clinton will do better than expected.