Wednesday, August 10, 2016

State Polls Then and Now

There is some talk these days about the shifting Electoral College map in 2016, based mostly on Clinton's poll numbers in states such as Arizona and Georgia.  One way to get a sense of how things are changing is to compare the most recent polling averages to the polling averages for the same states at this point in the campaign four years ago. The figure below compares the current (August 9, 2016) Pollster estimates of  Clinton's share of the two-party polling preference to Pollster's estimates of Obama's share of the two-party polling preference for the same states at this point in the campaign four years ago. This figure shows important signs of both continuity and change.

Continuity.  First, in terms of relative support, the picture is one of continuity: generally, the same states that gave Obama the greatest support in 2012 are still Clinton's biggest supporters, and those states that gave Obama the least support are also giving Clinton her lowest levels of support (the correlation between the two years is .87).  The bluest states from 2012 will still be really blue in 2016 and the reddest states will remain pretty red, with the exception, perhaps, of Utah, which may take on a pinkish hue.

Note: this figure only includes states for which there were Pollster estimates estimate for this point in time in both 2012 and 2016

Change. While the relative positioning of the states vis-à-vis each other has not changed much, there has been a fairly uniform shift among the states in Clinton's favor, reflecting her standing in national polls: across the nineteen states in the figure above the average level of support for Clinton in 2016 is roughly 2.4 points higher than the level of support for Obama at this point in the campaign, and  Clinton is doing better than Obama did in almost all states (states above the line of equality are states where Clinton is outperforming Obama at this point in the campaign).  Clinton is lagging behind Obama's pace in just three states--Nevada, New York, and Ohio--but still leads in these states, with only Nevada and Ohio close at this point.

Clinton's gains in Arizona (+4.4), Georgia (+3.7), North Carolina (+1.7), and Virginia (+2.6) are particularly notable as Virginia was narrow won by Obama in 2008 and 2012, North Carolina went for Obama in 2008 but not in 2012, and Georgia and Arizona have been somewhat out of reach for Democrats.  If Virginia becomes safe for Clinton and the battle for the Electoral College ends up being fought in places like North Carolina, Georgia, and Arizona, it's will be virtually impossible for Trump to carry the day. Utah also stands out as a big gain for Clinton (+17), no doubt in part due to Mitt Romney's vocal opposition to Donald Trump, but I doubt that it will actually be in play on election day.

Of course it is important to note that this analysis is limited to those states for which I could get polling averages from early August in both 2012 and 2016.  However, most of the remaining states are usually less competitive than those discussed above and there is less mystery about where they will end up on election day.

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