Every 10 years, states redraw their congressional district boundaries in response to population changes as reflected by the most recent decennial census. Each state is guaranteed at least one representative in the U.S. House, whereas larger, more populous states like California and Texas have the most representation in the lower chamber. The drawing of district boundaries is left up to individual states, the majority of which engage in a partisan redistricting process designed to create as many “safe” seats for like-minded partisans as possible. Partisan redistricting, or gerrymandering as it is commonly referred to, is often blamed for decreased levels of electoral competition, rising levels of incumbency reelection, and high levels of polarization in Congress.

In his new book, Nicholas Seabrook argues that much of the conventional wisdom about gerrymandering is misplaced. Whereas pundits and political observers are often quick to blame redistricting for many of the country’s woes, Seabrook maintains that partisan control of the redistricting process does not produce the significant and widespread electoral effects that are commonly attributed to it. Additionally, he contends that the consequences of partisan redistricting are not always negative, as many believe. As he describes early in Drawing the Lines, partisan redistricting is a fairly constrained activity with limited effects on both bias and responsiveness, especially since plans drawn by state legislatures often have to be approved by individual state governors. The author concludes that “partisan gerrymandering poses far less of a threat to democratic accountability than the conventional wisdom would indicate” (p. 11).

Seabrook’s analysis is organized in the following manner. In the first chapter, he presents his theoretical argument, in which he discusses the various constraints that political actors face in seeking to redraw district boundaries each decade. The fact that state legislatures do not uniformly control the redistricting process makes it more difficult for legislators to regularly implement plans that benefit fellow partisans. Additionally, he notes that any partisan bias introduced into the electoral system is likely to erode over time as a function of intradecade population migration, changing turnout patterns, and election swings, all of which can weaken the linkages between representatives and their constituents. When control of state governments is divided between the parties, he also notes that electoral competition is significantly reduced since both parties are forced to enact redistricting plans that seek to protect incumbents.

In the second and third chapters, Seabrook focuses more explicitly on the legal debates over partisan gerrymandering. Whereas some legal scholars have suggested that the Supreme Court has set too high a legal standard for finding evidence of partisan bias in past cases, the author disagrees. Based on a careful review of past decisions and case studies in both Pennsylvania and Texas, he argues that the main reason the Court has been reluctant to overturn state redistricting plans is that there is little or no evidence of long-term electoral disadvantage to one party or the other. As such, even though a state’s redistricting plan may favor a particular party in the short term, he maintains that such an advantage is often short-lived as a result of existing political constraints discussed in the first chapter.

In the fourth and fifth chapters, Seabrook conducts empirical analyses that test a variety of hypotheses discussed in the preceding chapters. In Chapter 4, he examines whether partisan redistricting creates long-term partisan advantages for one of the two major political parties. Compared with other, more neutral redistricting plans, Seabrook finds that partisan gerrymandering can produce a relatively small bias that favors the party that designed the congressional districts. In Chapter 5, he evaluates the relationship between redistricting and electoral responsiveness and district-level competitiveness. He concludes that partisan gerrymandering often leads to relatively few negative effects on legislative responsiveness. In fact, he argues in the conclusion that redistricting reform efforts should seek to generate greater levels of electoral competition in lieu of the bipartisan redistricting plans that are often adopted by state legislatures.

Seabrook’s analysis reminds us that although redistricting often is the source of blame for many of our country’s political problems, the story is far more complex than it first appears. Although he finds that partisan gerrymandering can indeed produce a short-term partisan bias in certain cases, such biases tend not to persist over time as a result of various institutional and electoral rules in place. In short, this timely book reminds us yet again that institutions matter in affecting political outcomes. The discussion also focuses on the legal implications of redistricting and demonstrates that the Court’s unwillingness to periodically wade into the political debate over gerrymandering is actually both defensible and understandable in light of the absence of long-term political consequences.

The previous discussion notwithstanding, Seabrook’s argument is not without its shortcomings. On the first page of the book, the author notes: “In 2003, the Texas Republicans, armed for the first time with control of both houses of the state legislature and the governorship, undertook an unprecedented mid-decade redrawing of the state’s congressional boundaries.” As Erik Engstrom demonstrates in Partisan Gerrymandering and the Construction of American Democracy (2013), mid-decade redistricting was quite common throughout the nineteenth century. In fact, state legislatures would often redraw congressional district boundaries during this era whenever they felt it would give them an advantage electorally. As Engstrom also notes on page 62 of his book, Ohio held six consecutive elections with six different redistricting plans between 1878 and 1892. All of which is to say that while what Texas did in 2003 may have caught many by surprise, it was not unprecedented; rather, it had historical analogs in the more partisan politics of the nineteenth century.

Additionally, Seabrook oversimplifies the underlying context associated with the debate over partisan gerrymandering and electoral competitiveness. There is considerable prior work that demonstrates that independent redistricting commissions lead to more competitive elections, but very little of that work is cited in this book. Furthermore, his discussion of partisan gerrymandering fails to capture the changing political implications of redistricting as reflected in the Supreme Court’s recent decision to hear oral arguments in Gill v. Whitford. Although the case focuses exclusively on Wisconsin’s redistricting plan in 2010, several political scientists have argued convincingly that the plan is extremely biased and detrimental to Democratic candidates in the state. If a majority of the Court ultimately agrees, the decision could have enormous implications for the practice of partisan gerrymandering throughout the rest of the nation. While some of Seabrook’s conclusions regarding the potential long-term consequences of partisan gerrymandering in certain states appear valid at face value, the specific mechanisms that underscore this relationship are only briefly mentioned by the author. Moreover, he fails to acknowledge the changing political context underlying the debate over partisan gerrymandering in light of recent events.

Still, Drawing the Lines does address a number of important issues and focuses on a timely subject, which makes it a worthwhile read for anyone who wants to learn more about the legal and political aspects of partisan gerrymandering in the United States.