How Many Seats in Congress Is Control of Redistricting Worth?

How large a benefit is partisan control of the redistricting process? Do legal constraints on redistricting—such as the preclearance requirement of the Voting Rights Act—alter this benefit? Are institutions designed to reduce the benefit to partisan control—such as redistricting commissions—effective? To measure the effects of partisan districting on the electoral fortunes of the parties, we collect data on the partisan composition of state government, House election outcomes, and moderating institutions over an 80-year period. Our results suggest that over time, both parties have benefited from unified control, with the effects largest in states where voters were evenly divided among the parties and smallest in states where the controlling party had a large advantage in the electorate. The effects have changed over time, with both parties having equally benefited from control during the middle of the 20th century, the benefit largely disappearing in the late part of the century, and the Republican Party seeing a moderate advantage from control in the current century. The benefits of partisan control were not diminished in states with redistricting commissions. The preclearance requirement appears to have hurt the Democratic Party except when its vote share was very low. The aggregate effects of partisan redistricting are moderate in magnitude—in the modern period, this effect has typically been less than 10 House seats, with the last election where control of the House would have flipped in expectation occurring in 1954.     

Small changes, big results: Legislative voting behavior in the presence of new voters

Changes in district boundaries in small magnitude electoral systems can have substantive consequences for representation. In the U.S., each decennial redistricting cycle infuses House districts with a large number of new voters, changing personal representation for many citizens. What effect does the influx of these new voters exert on member behavior? By assessing the extent of this change in constituencies in conjunction with member voting behavior on roll calls, we can determine if significant changes to a congressional district impact post-redistricting legislative behavior. Using panel data estimators and various measures of legislator behavior, we show evidence that supports this claim. Our findings have notable implications for debates over representation and electoral accountability in legislative assemblies.     

Partisan bias and redistricting in France

Decided by the executive, redistrictings in France have been claimed to have substantial partisan bias in favor of the right. We examine the evidence for this claim in terms of France's left bloc versus right bloc politics, combining information from both the first and the second round of France's two round electoral system. We also examine data at the constituency level to look at factors, such as malapportionment, that can affect bias. As France is characterized by a pattern of a limited number of redistrictings, population inequalities have grown in legislative constituencies between plans. Although the procedures used to draw constituency boundaries for the French Assembly are rather opaque, and under the control of political authorities, partisan bias appears as minuscule.     

Evaluating partisan gains from Congressional gerrymandering: Using computer simulations to estimate the effect of gerrymandering in the U.S. House

What is the effect of gerrymandering on the partisan outcomes of United States Congressional elections? A major challenge to answering this question is in determining the outcomes that would have resulted in the absence of gerrymandering. Since we only observe Congressional elections where the districts have potentially been gerrymandered, we lack a non-gerrymandered counterfactual that would allow us to isolate its true effect. To overcome this challenge, we conduct computer simulations of the districting process to redraw the boundaries of Congressional districts without partisan intent. By estimating the outcomes of these non-gerrymandered districts, we are able to establish the non-gerrymandered counterfactual against which the actual outcomes can be compared. The analysis reveals that while Republican and Democratic gerrymandering affects the partisan outcomes of Congressional elections in some states, the net effect across the states is modest, creating no more than one new Republican seat in Congress. Therefore, the partisan composition of Congress can mostly be explained by non-partisan districting, suggesting that much of the electoral bias in Congressional elections is caused by factors other than partisan intent in the districting process.