The shifts in outcomes between the 2008 presidential and 2009 gubernatorial elections in New Jersey and Virginia were driven far more by shifts in voting preferences among groups than by changes in turnout across those groups. Only age groups show consistently substantial changes in relative share of the electorate. Vote preference, in comparison, shows quite large shifts between election years. While one narrative of the 2009 election was changing turnout motivation, this turns out to be substantially false. Instead, changes in candidate preference drove the Republican wins in both New Jersey and Virginia.
The chart above shows the direction and size of change in vote preference for nine categories and 27 groups measured by exit polls in both years. The arrows start at the 2008 vote and point to the 2009 vote. The length of the arrow shows the amount of change and the arrow shows the direction of change. The colors code the shift in majority vote from 2008 to 2009. Blue indicates a Democratic majority for the group in both years. Red represents a Republican majority both years. Purple shows the groups that switched from a Democratic majority in 2008 to a Republican majority in 2009. None of the 27 groups switched from Republican to Democratic majorities.
In Virginia, large shifts in preference came among 18-29 year olds, those without a college degree, independents, rural voters and males. Smaller but still interesting changes came among lower and middle income voters, both of which shifted from majority Dem to majority Rep.
The most talked about shifts are among partisans and ideological groups. The large 16 point shift from 49 to 33 percent Dem among independents has justifiably received a lot of attention. But perhaps as interesting is the similarity of partisan loyalty among Dems and Reps. Neither shifted by enough to make the length of the arrow stand out. Virginia Democrats actually increased their Dem support by a point, while Republicans came home by a small 4 percentage points more than in 2008. Clearly the independents drove the dynamics of the outcomes.
Among conservatives, there was a modest shift of 9 points more Republican support in 2009, and a 5 point shift among moderates. Liberals moved a single point more Democratic.
By contrast, the shifts in share of the electorate were quite modest, as seen below.
By far the largest shifts are among the various age groups. The 18-29 year olds dropped 11 points, from 21 to 10 percent of the electorate. Those 30-44 also declined a bit, from 30 to 24 percent. These were matched by gains of 9 points among 45-64 year olds and of 7 points among those 65 and older. Age is one of the most potent predictors of turnout, and as this chart shows, one of the most dynamic from 2008-09.
The other two groups with interesting shifts are the rise in share of the electorate among conservatives (up from 33 to 40 percent of voters) and the similar decline in turnout among Democrats, from 39 to 33 percent.
Not only are these shifts substantial, but they also stand out against the very modest shifts in share of the electorate for all other groups. Many of the arrows have invisible lengths, indicating very small changes of one or two percent.
In New Jersey, we also see large preference shifts and even smaller turnout shifts.
The giant preference change in New Jersey is among independents, the same as Virginia. NJ independents took a massive 21 point shift from 51 percent for Obama to just 30 percent for Corzine. Also as in Virginia, Republicans came home to their party a bit, from a 14 percent defection rate for Obama to just 8 percent defection to Corzine. Democrats meanwhile barely budge, down from 89 to 86 percent Dem.
There were other substantial movements in vote preference, among 30-44 year olds, moderates, whites, hispanics and males. In short, many groups in New Jersey made substantial movements away from Democratic votes.
By contrast, the makeup of the New Jersey electorate changed a bit among age groups but hardly at all for virtually all other groups.
As with Virginia, there were declines in share of the electorate among 18-29 and 30-44 year olds and compensating increases among those 45 and above.
No other group comes close to such large changes in size. Several change by exactly zero (the open circles in the chart) and most others have lengths too small to see in the plot. The nearest exceptions are a decline of moderates of five percent and a corresponding five point rise among conservatives.
The bottom line for both states is that turnout changes were mostly about the age structure of the electorate. Younger voters are more responsive to short term stimulation, and in 2008 that translated to relatively large turnout, while in the absence of that stimulus in 2009 the more stable commitment to voting among those over 45 advantaged that group.
The shifts in preference in both states were significantly larger for many more groups. Preferences are driven by candidates and issues and those were the primary drivers of the change in outcomes from 2008 to 2009.
Below are alternative looks at the data, comparing the share and the vote for each state. These give a better look at the entire set of groups, but it is harder to compare magnitude of changes along the diagonal line in these charts than in the arrow plots above.