Keith T. Poole, Howard Rosenthal. Congress: A Political-Economic History of Roll-Call Voting. New York: Oxford University Press, 1997. x + 297 pp. $85.00 (cloth), ISBN 978-0-19-505577-1.
Reviewed by Jac Heckelman (Department of Economics, Wake Forest University)
Published on EH.Net (August, 1998)
Over the last decade and a half, Keith Poole and Howard Rosenthal have published several papers analyzing congressional roll-call voting behavior. In this new book, they pull together and extend this work, presenting their methodology and findings, and covering every Congressional roll-call vote from 1789 to 1985. The authors express their desire to make their research useful to economic historians. Fortunately, they have largely succeeded.
The main purpose of the book is to detail how roll-call voting is useful for determining legislators' ideological positioning in a spatial model. Their main conclusions are that: (1) ideology outperforms "economic" models of voting; (2) ideology is low dimensional; (3) ideological positions remain fixed throughout a legislator's tenure; and (4) mass political realignments among the voters are not matched by changes in roll-call voting except from the new legislators.
After a brief introductory chapter that nicely outlines the structure and highlights of the book, they present the basic methodology in Chapter Two. The spatial voting model they develop assumes that legislators will vote for or against an issue based on which side of the roll-call midpoint they are on, as expected by the Median Voter Theorem. Rather than rely on strict deterministic voting, the model instead is based on probabilistic voting where those closer to the option are more likely to vote for the option. Their model is supported by the finding that errors on predicted voting are primarily for those legislators close to the "cutting point" which identifies the location of the split between supporters and opponents. Although explicit details of the exact methodology may not be of particular interest to historians, it should be stressed that the only variable used is the actual roll-call votes. Poole and Rosenthal are correct to point out that their methodology is not very useful for predicting voting outcomes, rather it is designed for identifying the positions of each legislator and the cut point along the spatial dimension.
The next chapter presents evidence that ideology can readily be captured in only a single dimension and thus the simplest model can be estimated. A second dimension is only required in a few instances (discussed below) when racial issues are specifically involved. For those not interested in this finding, the chapter can be skipped without impeding the rest of the book.
Chapter Four is dedicated to the issue of party polarization. In this chapter the authors present a lot of stylized evidence, which makes for interesting reading. They conclude that Congress has been most polarized in the post-Reconstruction through WWI period, and least polarized in the post-WW II period, due to the North/South split in the Democratic Party. Poole and Rosenthal suggest the second dimension of race came into play due to civil rights issues in New Deal legislation which pushed the Southern Democrats further right in their ideological leanings. This interpretation is questionable since their analysis shows the first dimension movement actually began at the turn of the century and thus New Deal movement may only be the continuation of a prior trend. They also show that regional differences are not limited to the twentieth century. For example, Northern Whigs were consistently further right than Southern Whigs from 1827 to 1847, and the Whigs were further right than Democrats. But on slavery issues, the second dimension shows the southerners of both parties were more conservative than the northerners. Although most of the evidence is presented graphically throughout the book, this chapter is slightly marred by the inclusion of some ad hoc regressions which do not add much to the analysis.
The chapter on realignment is likely to be the most controversial among political historians. Political scientists typically refer to realignment as a change in voting behavior among the mass electorate, whereas Poole and Rosenthal define realignment as a change in roll-call voting. Their rationale for this new definition is as follows: "If an issue is to result in sustained public policies, we hypothesize that the policies must eventually be supported by a coalition that can be represented as a split on the first, or major dimension. Policy developed by coalitions that are non-spatial or built along the second dimension is likely to be transient and unstable" (p. 112). Under their definition, Poole and Rosenthal find that a legislative realignment occurred only once in U.S. history, this being in 1851-2 due to the extension of slavery to territories. This chapter is particularly strong on detailing the sequence of voting on slavery issues by party and region. Contrary to conventional wisdom, their analysis shows the realignment occurred before the Republicans became a strong political force in Congress. The findings of non-realignments are especially intriguing. Among many historians, the realignment of 1896 is considered a political fact. Poole and Rosenthal claim this to be a "false realignment" since only the importance of inflation changed, but not voting patterns on monetary issues. A regional East-West split remained but is captured in the first dimension and thus the model stays stable throughout this period. Similarly, the authors show the supposed "New Deal realignment" was simply a massive change in party composition in Congress, and thus a differing voting agenda occurred, but again roll-call behavior remained markedly stable among individual legislators. While I am certainly sympathetic to their interpretation, I expect traditional political historians are unlikely to be convinced and may cite this instead as evidence that Congressional realignment is less important to determining the direction of the nation than traditional analysis of the mass electorate. Finally, Poole and Rosenthal uncover a slight "perturbation" in the 1950s as civil rights issues split the Democratic party, but this is directly captured by including a second dimension to voting and never dominates the first dimension voting on traditional economic issues.
After the excitement of turning realignment theory upside-down, things return to a more mundane level in chapter 6 where it is shown that the senators from a given state (and party) do not typically vote the same way. This is given as evidence that legislators vote based on their individual ideology, and spatial ideology outperforms the purely economic median voter models. Once ideology is included, there is weak correlation of the residuals by state. Case studies are presented for food stamp programs in 1964 and 1967, railroad regulation from 1874 to 1887, legislation on the minimum wage from 1937 to 1990, strip mines in 1974 and OSHA in 1975. These results are well established in the literature, and their presence here serves only to reiterate the findings (some of which are their own from earlier studies).
The issue of strategic voting is finally considered in Chapter 7 where we learn that cases of strategic voting throughout history are extremely rare. It is unfortunate that this important topic is relegated to its own chapter toward the end of the book, as the interpretation of ideology would be altered if legislators engaged in strategic voting. Furthermore, the authors incorrectly argue that strategic voting should not occur in single dimensional space, and therefore only consider the cases when race creates a second dimension. This conclusion is valid only if legislators have single-peaked preferences in their utility functions. If preferences are not single-peaked, cycling and strategic voting are still possible even in a single dimension. Although single-peaked preferences are an explicit assumption of their model, this was presented at the start of the book and needs to be reiterated here. If this assumption fails to hold, strategic voting may be more problematic than they allow for. The chapter includes only brief discussions of strategic voting in the political science literature, which includes (in order of presentation) the 1965 School Aid Bill and Powell Amendment, the 1846 Wilmot Proviso, and the 1911 DePew Amendment.
Scholars often measure legislator ideology from various interest-group ratings, which only consider a subset of votes in any year. Chapter 8 shows a high degree of correlation between the most commonly utilized ratings and Poole and Rosenthal's predicted scores based on all votes. This is an important finding since interest group ratings are not available prior to the 1960s.
The last two chapters on committee representation and legislator abstention, are unlikely to be of specific interest to historians as they only present broad trends and do not include the insightful discussions of individual historical case studies of the previous chapters.
The flaws discussed above are minor compared to the great strengths of the book. The book is highly recommended for anyone interested in the history of roll-call voting and the careful analysis of legislator ideology.
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Jac Heckelman. Review of Poole, Keith T.; Rosenthal, Howard, Congress: A Political-Economic History of Roll-Call Voting.
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