Rethinking redistricting and when it matters

By Charles R. Hunt

In a previous LegBranch post, I  assessed some competing theories of how consequential the redistricting process has been to congressional elections over the past couple of decades. A sharp (and sometimes heated) debate on the subject continues. But too often, redistricting is described as a “one-size-fits-all” phenomenon, affecting all types of voters equally and with the same  results. In a recently-published article in Electoral Studies, I break down the effects of redistricting on the individual voter to predict how and for whom redistricting has the greatest impact. The findings – that redistricting has consequences for some voters, but not for others – should induce politicians, pundits, and congressional scholars to rethink what it really means to be “redistricted.”

What does redistricting change for voters?

When redistricting occurs, nearly every voter’s district changes in some way. Previous work has considered how redistricting can upend important elements of the electoral process for many voters. In this project, I disentangled three of these elements to see which changes affect voters the most. To do this, I used the Florida voter file and geographic analysis software to pinpoint Florida voters and assess how much their districts changed based on three elements: competitiveness, incumbency, and partisanship.

These are critical factors in congressional elections because all three have significant effects on turnout. More competitive districts, for example, generate greater campaign activity, stronger candidates, and increased probability of one’s vote being “decisive” in the election. Incumbency, too, is thought to positively affect turnout via the “personal vote,” wherein longtime voters are personally motivated to turn out. And upending partisan balance in the district can remove simple cues that voters use to motivate them to vote and decide for whom to vote.

Redistricting, to varying extents, changes all of these elements in ways that could dampen an individual voter’s motivation to turn out on Election Day. But which voters are affected the most, and how much?

Which voters are most “susceptible” to the process?

I ran models estimating a voter’s probability of turning out in the 2012 election based on redistricting-induced changes in district-level competitiveness, incumbency, and partisan balance. The results indicate that changes in competitiveness or incumbency are minimal for the average voter, resulting in less than a 1 percent decrease in probability of voting. Changes in partisan balance of their district, on the other hand, decrease the average voter’s turnout probability by nearly 3 percent. Partisan change even affects unaffiliated voters by the same amount, indicating that these changes have underlying effects on district-wide political culture.

But not all voters are affected equally by redistricting-induced changes. The most striking difference was between high-propensity voters with a strong history of turnout, and low-propensity voters. As expected, high-propensity voters are likely to turnout regardless of changes redistricting brings. Low-propensity voters, on the other hand, are much more easily affected by these changes: large changes in the partisanship of their district, for example, decrease their probability of voting by nearly 5 percent.

So, does redistricting matter for turnout?

Admittedly, single-digit changes in turnout probability do not seem all that significant. For many voters, especially highly engaged ones, redistricting is unlikely to have a huge impact on turnout. But in close contests, these fluctuations can easily swing an election. Many, for example, predict that the 2018 elections will hinge on the turnout of previously-unengaged Democratic voters. Secondly, since this project predicts turnout in Florida in 2012 — a presidential year in a swing state — it represents a very conservative test of the effects of redistricting on turnout. Perhaps the voters, and not just the legislators, should receive top consideration when the next round of redistricting occurs.

Charles Hunt (@charlesrhunt) is a Ph.D. candidate at the University of Maryland, College Park.