Introduction

Every decade, following the U.S. Census, states redraw the boundaries of their congressional and state legislative districts. This redistricting process can have tremendous consequences for how communities, voters, and parties are represented in both Congress and state legislatures. It can create competitive races, or insulate incumbents from competition. It can divide communities and cities or keep communities and cities together. Redistricting can also give one party disproportionate representation, far beyond the share of the votes it receives. These contortions and distortions collectively go under a single epithet: “gerrymandering.”

Because many view gerrymandering as both out of control and destructive to American democracy, eight states have now taken redistricting authority away from state legislatures and handed it over to independent citizens commissions.¹ In widespread commentary, analysts who bemoan the evils of gerrymandering typically recommend commissions as the obvious alternative. The conventional wisdom is that commissions are better able to make districting “fair.”

This report offers a systematic analysis of the claim that redistricting commissions can improve the fairness of redistricting.

The simple takeaway is that redistricting commissions are superior to partisan legislatures across any number of measures. However, many of the problems attributed to gerrymandering are actually problems with districting, and more specifically with the use of the single-member district. Thus, while redistricting commissions do perform better than partisan state legislatures, the improvements are typically more marginal than the conventional wisdom would suggest, and they fall short of ideal conditions—especially when it comes to the share of districts that are competitive in a general election. Even in states that use independent commissions, barely one-in-ten districts are two-party competitive.

This report aims first to provide a detailed framework for evaluating redistricting plans; and second, to then evaluate the performance of commissions within this framework. In so doing, we are forced to confront the severe limits of districting within the single-member district framework.

Gerrymandering is an obvious bad, primarily because it allows a party in power to entrench and distort its majority by changing district lines to most efficiently distribute its voters, sometimes creating an imbalance in which a party that gets a minority of votes can win a majority of seats in a legislature, in obvious violation of a basic democratic principle that the party that gets more votes should win the election. Independent redistricting commissions, particularly those fully insulated from partisan politics, are a logical, appropriate, and effective solution.

However, many of the other problems ascribed to gerrymandering, particularly the decline of competitive districts, are in fact problems of single-member districting under geographically polarized parties, and therefore are not areas where independent commissions can make more than marginal progress.

Evaluating the work of commissions is further complicated by the simple reality that not all commissions have the same structure or authority. Some redistricting commissions have more independence from partisan politics and elected officials than others. How commissions are selected matters. So does their power.

Additionally, state laws direct commissions to prioritize among competing goals in districting. All districting plans force trade-offs between five main goals: partisan neutrality, competitiveness, compactness, keeping communities of interest together, and fair minority representation.

Furthermore, all five goals of redistricting lack agreed-upon metrics. At least 18 different measures of partisan fairness have been proposed, as have almost 100 measures of compactness, and countless measures of competitiveness and community integrity. Because fair minority representation has been the most litigated area, it has historically had more agreed-upon metrics. But even here, the standards are changing and eroding.²

Finally, as partisanship and demographics continue to shift, the possibilities of districting continue to change. Particularly, as the urban-rural divide continues to deepen in American politics,³ as cities and inner suburbs become more multiracial and cosmopolitan, and as the hyper-partisan intensity of narrowly contested elections continues to deepen, commissions must navigate the difficulties of drawing fair districts under such conditions. When Democrats and Republicans live in different places, competition and partisan neutrality are extremely difficult to negotiate. Competition is extremely difficult to achieve generally, and partisan neutrality becomes deeply contested.

Moreover, districts change over the course of a 10-year districting cycle. Districts that appear safe at the beginning of the decade may become competitive by the end. Districts that appear competitive may become safe for one party or the other.

This report shows the limits of what is possible under a framework of single-member districts and provides reasonable expectations for what redistricting commissions can actually accomplish within this framework. Many of the problems that we think independent commissions could solve are not caused by gerrymandering per se but are unavoidable within the context of single-member districts. But independent commissions can lead to modest improvements.