Plotted below are median Clinton-minus-Trump margins in all states for which August polling is available, plotted against Obama-over-Romney margins at the same point in the 2012 campaign. This horizontal axis quantity is better to plot than the final Obama-Romney election margins, which include undecided voters’ final commitments – not a fair comparison.http://election.princeton.edu/2016/08/16/clinton-runs-5-8-po...
The data come from RealClearPolitics.
Clinton is overperforming Obama in 14 out of 16 states, the significant exceptions being deeply Democratic Maine and New York. Overall, the difference is a median of 5.8 +/- 1.4% (estimated one-sigma SEM).
I didn't expect that, but I'm sure it's due more to dislike of Trump, than like of Hillary.