Political Science Redistricting and Electoral Competition in American Politics
Ryan Williamson
  • LAST MODIFIED: 28 August 2019
  • DOI: 10.1093/obo/9780199756223-0279


Redistricting, or the process of redrawing congressional district boundaries, can be a highly contentious and political affair. Electoral competition within districts is dependent on both of the major American political parties being evenly balanced. Therefore, redistricting can enhance or diminish competition through how it distributes partisans across districts. Indeed, politicians have used this process to manipulate boundaries in their favor for centuries. In fact, the term most commonly used for exploiting the redistricting process for partisan gain—gerrymandering—was coined in 1812 as Massachusetts governor Elbridge Gerry signed legislation creating a map with heavily distorted districts, one of which resembled a salamander. Thus, the portmanteau “gerry-mander” was born. The misshapen districts produced the intended effect of facilitating greater electoral success for members of the governor’s party. Throughout history, Congress, the US Supreme Court, individual states, the American electorate, and an ever-evolving political environment have all impacted the construction of district maps. Additionally, each of these factors further influences the level of electoral competition within the district. Therefore, this work seeks to outline how redistricting can directly or indirectly influence electoral competition within congressional districts. Directly, different redistricting entities (legislatures, commissions, and courts) possess different motivations and constraints when drawing district lines, which can impact competition. Indirectly, redistricting can influence voting behavior and the incumbency advantage, which can also impact competition. This work also explores the tradeoff between representation and competition, the relationship between redistricting and polarization, what constitutes a gerrymander, and how durable redistricting plans are over time. Each can have a substantial impact on electoral competition, which in turn bears consequences for our understanding of the consequences of redistricting.

Partisan Redistricting and Competition

The effects of partisan redistricting on competition are not a settled matter. Conclusions cover the entire spectrum of no effects, positive effects, negative effects. There is, however, agreement that the overall levels of competition within congressional elections has declined in recent decades, as demonstrated by Ferejohn 1977 and Abramowitz, et al. 2006. However, as McDonald 2006 shows, this conclusion is dependent on measurement. In a similar vein, Engstrom 2006 turns to an analysis of 19th-century redistricting plans to gain additional leverage on this question. Conversely, some researchers have found the opposite effect—that partisan redistricting is beneficial to elections, such as Gelman and King 1994 and Yoshinaka and Murphy 2011. These findings suggest that, though counterintuitive, partisan redistricting plans can produce positive effects on election outcomes. Winburn 2008 suggests that the effect is dependent on the rules and constraints placed on the state legislature. Regardless of the effect on competition, Buchler 2005 and Brunell 2008 defend a lack of competitiveness as a potentially positive attribute, contrary to the popular conception of competition as necessary for a healthy democracy. These authors suggest that competition is not the variable of interest when evaluating redistricting plans, but the effects on representation should instead be considered.

Courts, Competition, and Redistricting

At times, the legality of redistricting plans comes under scrutiny. In those instances, the judicial branch must intervene, but the effects courts have on the redistricting process vary. Some evidence, like that of Cottrill and Peretti 2013, suggests that courts are constrained by legal standards and must act as neutral arbiters when considering district maps. This in turn increases the overall level of competition. However, others acknowledge that judges are political actors seeking to assist like-minded political actors in other branches of government, such as Lloyd 1995. Others, like McKenzie 2012, offers a more nuanced perspective. In an indirect way, the courts have shaped how redistricting can impact competition through deciding what constitutes an unlawful partisan gerrymander. Issacharoff and Karlan 2004; Hirsch 2003; and McGann, et al. 2016 provide useful context related to redistricting court cases as well as offer potential remedies and justifications for combatting gerrymandering. Furthermore, one of the primary issues courts must consider regarding redistricting cases is adherence to the one person, one vote standard, which requires districts to have as close to equal populations as possible. Persily, et al. 2002 provides an interesting discussion of the electoral consequences of this standard.

Redistricting Commissions and Their Effects

One of the common means by which reformers hope to reduce or eliminate partisanship from the redistricting process is through empowering a commission instead of the state legislature when constructing district maps. Evidence about the effect of commissions is somewhat mixed. Some argue that since commissions are not motivated by partisan gain, they are able to draw maps in such a way that fosters greater competition. This argument is supported by Carson, et al. 2014 and Lindgren and Southwell 2013. Cottrill 2012 and Edwards, et al. 2017 also reach conclusions that support the idea that non-legislative-based plans increase competition in various ways. Conversely, others, such as Masket, et al. 2012 and Henderson, et al. 2018, contend that overall competition is unaffected by different redistricting methods.

Measuring Gerrymandering

Though claims of gerrymandering are common, the ability to objectively identify what actually constitutes a gerrymander can be a difficult task. The natural geography of a state or the creation of a majority-minority district can produce a uniquely misshapen district. Nonetheless, many have argued that creating compact districts is one mechanism by which gerrymandering can be constrained, which should increase competition. The logic is straightforward—more compact districts do not possess the irregular protrusions of gerrymandered districts. Altman 1998, however, demonstrates that the relationship is not clear. Another shortcoming regarding the use of compactness to measure gerrymandering is offered by Young 1988. Another factor that complicates how to evaluate gerrymandering is presented in Chen and Cottrell 2016, which supports earlier findings from Chen and Rodden 2013. Given the difficulties of measuring compactness, Niemi, et al. 1990 suggests considering multiple measures simultaneously in order to appropriately assess district shapes. In an effort to measure gerrymandering without considering compactness, Stephanopoulos and McGhee 2015 introduced the efficiency gap. Another way scholars have tried to identify gerrymandering is through the fracturing of “communities of interest.” The logic is that splitting regions that would otherwise intuitively be drawn together typically indicates an attempt at creating partisan bias. However, there is no standard definition of community of interest. Makse 2012, Phillips and Montello 2017, and Stephanopoulos 2012 each provide different suggested definitions. However, all three agree that adherence to preserving communities of interest should curb gerrymandering. This is important as Cox and Katz 1999 shows a strong link between redistricting and bias. Taken together, these works show the difficulties in empirically assessing gerrymandering, which further inhibits the ability of researchers to evaluate the relationship between redistricting and competition.

  • Altman, Micah. “Modeling the Effect of Mandatory District Compactness on Partisan Gerrymanders.” Political Geography 17.8 (1998): 989–1012.

    DOI: 10.1016/S0962-6298(98)00015-8Save Citation »Export Citation »E-mail Citation »

    This work shows that compactness standards can reduce gerrymandering, but only if states impose a strict definition of compactness.

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  • Chen, Jowei, and David Cottrell. “Evaluating Partisan Gains from Congressional Gerrymandering: Using Computer Simulations to Estimate the Effect of Gerrymandering in the US House.” Electoral Studies 44.2 (2016): 329–340.

    DOI: 10.1016/j.electstud.2016.06.014Save Citation »Export Citation »E-mail Citation »

    These authors use computer simulations to evaluate redistricting plans and discover that most bias and lack of competition is a product of like-minded partisans concentrating themselves in close geographic proximity.

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  • Chen, Jowei, and Jonathan Rodden. “Unintentional Gerrymandering: Political Geography and Electoral Bias in Legislatures.” Quarterly Journal of Political Science 8.3 (2013): 239–269.

    DOI: 10.1561/100.00012033Save Citation »Export Citation »E-mail Citation »

    These authors state that Democrats are inefficiently distributed across the country, which subsequently leads candidates of that party winning more votes but fewer seats, even absent gerrymandering.

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  • Cox, Gary W., and Jonathan N. Katz. “The Reapportionment Revolution and Bias in U.S. Congressional Elections.” American Journal of Political Science 43.3 (1999): 812–841.

    DOI: 10.2307/2991836Save Citation »Export Citation »E-mail Citation »

    Using a formal model, these authors find strong evidence that partisan control has a direct impact on the redistricting process and can induce bias in subsequent election outcomes.

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  • Makse, Todd. “Defining Communities of Interest in Redistricting Through Initiative Voting.” Election Law Journal 11.4 (2012): 503–517.

    DOI: 10.1089/elj.2011.0144Save Citation »Export Citation »E-mail Citation »

    This work attempts to offer a definition of a “community of interest” in order to evaluate redistricting plans. Specifically, he argues for the use of statewide initiative votes as they are not partisan, but still political, decisions.

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  • Niemi, Richard G., Bernard Grofman, Carl Carlucci, and Thomas Hofeller. “Measuring Compactness and the Role of a Compactness Standard in a Test for Partisan and Racial Gerrymandering.” Journal of Politics 52.4 (1990): 1155–1181.

    DOI: 10.2307/2131686Save Citation »Export Citation »E-mail Citation »

    The authors suggest using a variety of different measures (as opposed to a single measure) to evaluate entire districting plans (as opposed to individual districts) in order to effectively capture this difficult concept.

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  • Phillips, Daniel W., and Daniel R. Montello. “Defining the Community of Interest as Thematic and Cognitive Regions.” Political Geography 61 (2017): 31–45.

    DOI: 10.1016/j.polgeo.2017.06.005Save Citation »Export Citation »E-mail Citation »

    These authors attempt to offer a definition of “communities of interest” in order to evaluate redistricting plans. They analyze thematic regions (those distinguished by demographics) and cognitive regions (those distinguished by commonly agreed upon criteria) and find that the two correspond well.

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  • Stephanopoulos, Nicholas O. “Redistricting and the Territorial Community.” University of Pennsylvania Law Review 160 (2012): 1379–1478.

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    This work attempts to offer a definition of a “community of interest” in order to evaluate redistricting plans. By relying on “organic geographic communities,” the author contends that this metric helps identify unlawful gerrymanders, which when employed, would, at least theoretically, decrease partisan bias and increase electoral responsiveness and voter participation.

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  • Stephanopoulos, Nicholas O., and Eric M. McGhee. “Partisan Gerrymandering and the Efficiency Gap.” University of Chicago Law Review 82 (2015): 831–900.

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    This measures the number of “wasted” votes for both parties in an election relative to the number of votes cast. A competitive election would see very few wasted votes by the winning party, but an uncompetitive election would see many more wasted votes. Using this metric, they conclude that the most recent round of redistricting produced the most extreme gerrymanders in modern history.

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  • Young, H. P. “Measuring the Compactness of Legislative Districts.” Legislative Studies Quarterly 13.1 (1988): 105–115.

    DOI: 10.2307/439947Save Citation »Export Citation »E-mail Citation »

    The author contends that the definition of “compact” varies so greatly across states and the concept is so imprecise that it cannot serve as a reasonable standard when evaluating district boundaries.

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Redistricting, Representation, and the Voting Rights Act

As previously mentioned, the redistricting process often involves tradeoffs between inducing competitive elections and representative outcomes. At least part of this is governed by the Voting Rights Act, which mandates that some states create majority-minority districts. These are districts in which a majority of the population is made up of a racial minority group or groups. However, these districts have other consequences at well, according to Bullock 2010. Cameron, et al. 1996 expands on this by exploring the tradeoffs of substantive and descriptive representation, and their findings are echoed later in Epstein, et al. 2007. Lublin 1997 reaches a similar conclusion in and argues for a way to balance descriptive and substantive representation. The composition of districts is important, as demonstrated by Canon 1999. Additionally, ensuring minority representation through the construction of these districts can at times be at odds with other redistricting principles. In this vein, Barabas and Jerit 2004 and Bowen 2014 explore some of the tradeoffs between representation and district shape. In totality, these works show that the pursuit of increasing other important factors, like representation, can decrease the number of competitive elections.

  • Barabas, Jason, and Jennifer Jerit. “Redistricting Principles and Racial Representation.” State Politics & Policy Quarterly 4.4 (2004): 415–435.

    DOI: 10.1177/153244000400400404Save Citation »Export Citation »E-mail Citation »

    This research finds that drawing more compact districts decreases the ability of racial minorities to influence elections in their districts.

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  • Bowen, Daniel C. “Boundaries, Redistricting Criteria, and Representation in the U.S. House of Representatives.” American Politics Research 42.5 (2014): 856–895.

    DOI: 10.1177/1532673X13519127Save Citation »Export Citation »E-mail Citation »

    This work shows that more compact districts result in better communication with and responsiveness from representatives.

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  • Bullock, Charles S. Redistricting: The Most Political Activity in America. Lanham, MD: Rowman & Littlefield, 2010.

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    This book argues that majority-minority districts ultimately had the unintended consequence of “bleaching” the surrounding districts, which led to more white, typically Republican, candidates winning elections.

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  • Cameron, Charles, David Epstein, and Sharyn O’Halloran. “Do Majority-Minority Districts Maximize Substantive Black Representation in Congress?” American Political Science Review 90 (1996): 794–812.

    DOI: 10.2307/2945843Save Citation »Export Citation »E-mail Citation »

    They argue that majority-minority districts increase descriptive representation (electing more minority candidates) at the expense of substantive representation in surrounding districts (influencing the vote of representatives).

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  • Canon, David T. Race, Redistricting, and Representation: The Unintended Consequences of Black Majority Districts. Chicago: University of Chicago Press, 1999.

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    This book shows that majority-black districts actually serve white constituents quite well since primary elections in majority-black districts feature numerous black candidates, which fractures support among candidates within that voting group. Therefore, the successful candidates are generally the ones that appeal to white voters in order to secure their party’s nomination.

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  • Epstein, David, Michael C. Herron, Sharyn O’Halloran, and David Park. “Estimating the Effect of Redistricting on Minority Substantive Representation.” Journal of Law, Economics, and Organization 23.2 (2007): 488–518.

    DOI: 10.1093/jleo/ewm031Save Citation »Export Citation »E-mail Citation »

    This work corroborates earlier findings that practices that elect more minority candidates can actually decrease the quality of representation provided to minority communities.

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  • Lublin, David. The Paradox of Representation: Racial Gerrymandering and Minority Interests in Congress. Princeton, NJ: Princeton University Press, 1997.

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    This book suggests that redistricting plans should seek to strike a balance between the number of majority-minority districts and the number of districts with only 40 percent minority populations that can influence representatives.

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Redistricting and its Impact on Citizens

Another way redistricting can impact the competitiveness of elections is through influencing the behavior of voters. By affecting who votes in elections, the redistricting process similarly affects who runs and ultimately wins elections. Hayes and McKee 2009 and Hunt 2018 find that redistricting can depress turnout. The effect of redistricting on turnout varies across groups though, as demonstrated by Barreto, et al. 2004. However, evidence is mixed as Fraga 2016 reaches the opposite conclusion. Henderson, et al. 2016 suggests both may be correct to a certain extent depending on the state being observed, and Fraga 2016, furthermore, finds different effects for different groups. Beyond the population composition of a district, the physical boundaries themselves can also impact participation in elections according to Ladewig 2018. However, other factors impacting the shape of a district do not have the same effect, as Winburn and Wagner 2010 contends. Lastly, redistricting can enhance or disrupt a sense of community among voters, but the relationship is unsettled. Christenson and Makse 2015 finds that voters generally prefer a sense of shared representation at the expense of compactness or copartisanship. However, Winburn, et al. 2017 finds that citizen mapmakers display a preference for partisanship over the preservation of communities. This difference is unsurprising, however, given the findings of Fougere, et al. 2010 that voters are typically uninformed of the redistricting process.

Redistricting and Polarization

Despite popular conceptions and narratives, redistricting seems to have little to no substantial impact on the level of political polarization seen in American politics. Theriault 2008 provides a comprehensive summary, and his argument of no relationship between redistricting and polarization is echoed by McCarty, et al. 2009. Additionally, as Ryan and Lyons 2014 concludes in an analysis, “limiting gerrymandering is not a solution for polarization” (p. 234). Nonetheless, an alternative perspective is offered by Brunell and Buchler 2009, which largely comports with Caughey, et al. 2017, whose authors provide suggestive evidence of a relationship between redistricting and polarization. Specifically, they demonstrate that electing Democrats leads to more liberal policies being enacted and that this effect has grown over time. Finally, Carson, et al. 2007 offers a more nuanced perspective, which suggests that redistricting can have a marginal effect but is not a primary factor.

Redistricting and the Incumbency Advantage

One of the primary ways redistricting impacts competition and election outcomes is through creating safe districts for incumbents, who already enjoy an advantage over challengers. Tufte 1973 was one of the first to make this argument. However, much of the work since then, such as Desposato and Petrocik 2003 and Hood and McKee 2010, reaches a different conclusion. Given how redistricting can actually make an incumbent more vulnerable as these previous works show, Friedman and Holden 2009 argues, “changes in redistricting have reduced the probability of incumbent reelection over time” (p. 593). This argument is furthered by Crespin and Edwards 2016, which finds that donors are less likely to give to a candidate out of their district. The redistricting process does not affect all incumbents equally though, as demonstrated by Murphy and Yoshinaka 2009. Additionally, Boatright 2004 and Crespin 2010 suggest that incumbent members of Congress will change or modify their behavior, voting and otherwise, in order to better align with their districts and improve their chances of winning re-election. Moreover, Cox and Katz 2002 provide the most robust evaluation of the relationship between incumbency and redistricting in their book.

The Durability of Redistricting Plans

Redistricting generally occurs every ten years, but circumstances can drastically change between cycles. Niemi and Winsky 1992 offer one such example. Altman, et al. 2005 demonstrates that the practice of redistricting has become increasingly sophisticated with advances in computer technology. However, more precise maps are also more sensitive to changes in populations and political conditions over the course of a decade, which can produce different election outcomes within the same districts. In this vein, Seabrook 2017; Goedert 2017; and Hetherington, et al. 2003 all demonstrate how factors influencing competitiveness vary over the life of a redistricting plan. In their analysis of 19th-century elections, Carson, et al. 2006 reaches similar conclusions. Indeed, as Makse 2014 demonstrates, control of the redistricting process is such a valuable tool that “majority-seeking behavior [of the state legislature] is more intense . . . when redistricting is imminent” (p. 342) Though redistricting generally occurs once every decade, states sometimes redraw boundaries mid-cycle without new census information. Levitt and McDonald 2007 outlines the various state constitutional provisions that parties exploit to this end, and Engstrom 2013 illustrates that parties commonly redrew congressional boundaries mid-cycle in the 19th century.

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