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9 - Polarization in American State Legislatures


Published online by Cambridge University Press:  05 November 2015

Boris Shor
Georgetown University
James A. Thurber
American University, Washington DC
Antoine Yoshinaka
State University of New York, Buffalo
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  1. • New measures of state legislative polarization show that Democrats and Republicans continue to diverge, although more quickly in some states than in others. Levels of polarization in many states exceed that of Congress.

  2. • No one “smoking gun” explains state legislative polarization. In many cases, we can only rule out suspected causes such as primaries. However, interesting new evidence implicates specific forms of opinion polarization and income inequality.

  3. • The consequences of state legislative polarization are only now beginning to be explored. Increasing unilateralism by governors appears to be one major implication of increased gridlock within the legislature.

  4. • Major advances in our understanding of polarization are more likely to come from the states compared with Congress, given the tremendous institutional and preference variation in the former compared with the latter


Most of the recent scholarly literature on Congress emphasizes trends that indicate rising party differences in roll call voting behavior (Poole and Rosenthal 1997; McCarty, Poole and Rosenthal 2006). These findings are generally based on measures of positions on the liberal-conservative continuum as revealed through roll call voting. Although various techniques for measuring the ideology of legislators have been developed, they all produce very similar findings. The measure of polarization I use in this chapter is the difference in medians between Democrats and Republicans, with a larger gap indicating a greater level of polarization.

Why do we care about polarization? Excessive levels of partisanship and ideological polarization have been shown to have a pernicious effect on many aspects of policymaking and governance (see McCarty, Poole, and Rosenthal 2006, 2013, and Barber and McCarty 2015 for a review of the evidence at the national level). As recent events in many state capitols attest, these problems are beginning to afflict policymaking at the state level. As a result, a robust public debate about how to reduce polarization and partisanship has emerged.

What about American state legislatures? Are they polarizing like Congress? It is important to quantify such trends because we want to know if polarization is leading to political gridlock and dysfunctional policy. We also need a barometer of polarization to find out whether institutional reforms such as opening up primaries, taking redistricting away from politicians themselves, setting term limits, and so forth can ameliorate this phenomenon.

American Gridlock
The Sources, Character, and Impact of Political Polarization
, pp. 203 - 221
Publisher: Cambridge University Press
Print publication year: 2015

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Aldrich, John H., and Battista, James S. Coleman. 2002. “Conditional Party Government in the States.” American Journal of Political Science 46 (1): 164–172.CrossRefGoogle Scholar
Barber, Michael, and McCarty, Nolan M. 2015. “Causes and Consequences of Political Polarization.” In Persily, Nathaniel, ed., Solutions to Political Polarization in America. Cambridge: Cambridge University Press.Google Scholar
Bullock, Will, and Clinton, Joshua D. 2011. “More a Molehill Than a Mountain: The Effects of the Blanket Primary on Elected Officials’ Behavior from California.” Journal of Politics 73 (3): 915–930.CrossRefGoogle Scholar
Calvert, Randall L. 1985. “Robustness of the Multidimensional Voting Model: Candidate Motivations, Uncertainty, and Convergence.” American Journal of Political Science 29(1): 69–95.CrossRefGoogle Scholar
Deering, Christopher J. and Maltzman, Forrest. 1999. “The Politics of Executive Orders: Legislative Constraints on Presidential Power.” Political Research Quarterly 52 (4): 767–783.CrossRefGoogle Scholar
Ferguson, Margaret,and Shor, Boris. 2014. “Unilateral Lawmaking in the American Governorship.” Working paper.
Fiorina, Morris P., and Abrams, Samuel J.. 2008. “Political Polarization in the American Public.” Annual Review Political Science 11: 563–588.CrossRefGoogle Scholar
Frank, Mark W. 2014. “A New State-Level Panel of Annual Inequality Measures over the Period 1916–2005.” Journal of Business Strategies 31 (1): 241–263.Google Scholar
Garand, James C. 2010. “Income Inequality, Party Polarization, and Roll-call Voting in the US Senate.” The Journal of Politics 72 (4): 1109–1128.CrossRefGoogle Scholar
Gerber, Alan. 1998. “Estimating the Effect of Campaign Spending on Senate Election Outcomes Using Instrumental Variables.” American Political Science Review 92 (2): 401–411.CrossRefGoogle Scholar
Gilbert, Craig. 2014. “Legacy of Wisconsin's Polarization: No Consensus, Little Common Ground.” Wisconsin Journal-Sentinel, May 13.
Gray, Virginia, Cluverius, John, Harden, Jeffrey, Shor, Boris, and Lowery, David. 2014. “Party Competition, Party Polarization, and the Changing Demand for Lobbying in the American States.” American Politics Research 43 (2): 175–204.Google Scholar
Gray, Virginia, and Lowery, David. 2000. The Population Ecology of Interest Representation: Lobbying Communities in the American States. Ann Arbor: University of Michigan Press.Google Scholar
Gray, Virginia, Lowery, David, and Benz, Jennifer K. 2013. Interest Groups and Health Care Reform Across the United States. Washington, DC: Georgetown University Press.Google Scholar
Hall, Andrew B. 2014. “How The Public Funding of Elections Increases Candidate Polarization.” Working paper
Howell, William G. 2003. Power without Persuasion: The Politics of Direct Presidential Action. Princeton, NJ: Princeton University Press.CrossRefGoogle Scholar
Kousser, Thad, Phillips, Justin H., and Shor, Boris. 2014. “Reform and Representation: Assessing Californias Top-Two Primary and Redistricting Commission.” Working paper.
Masket, Seth. 2009. No Middle Ground: How Informal Party Organizations Control Nominations and Polarize Legislatures. Ann Arbor: University of Michigan Press.CrossRefGoogle Scholar
Masket, Seth E., and Shor, Boris. 2015. “Polarization without Parties: The Rise of Legislative Partisanship in Nebraskas Unicameral Legislature.” State Politics and Policy Quarterly 15 (1): 69–90.CrossRefGoogle Scholar
McCarty, Nolan, Poole, Keith T., and Rosenthal, Howard. 2013. Political Bubbles: Financial Crises and the Failure of American Democracy. Princeton, NJ: Princeton University Press.Google Scholar
McCarty, Nolan, Poole, Keith T. and Rosenthal, Howard. 2009. “Does Gerrymandering Cause Polarization?American Journal of Political Science 53 (3): 666–680.CrossRefGoogle Scholar
McCarty, Nolan, Poole, Keith T., and Rosenthal, Howard. 2006. Polarized America: The Dance of Ideology and Unequal Riches. Cambridge, MA: MIT Press.Google Scholar
McGhee, Eric, Masket, Seth E., Shor, Boris, Rogers, Steven, and McCarty, Nolan M.. 2014. “A Primary Cause of Partisanship? Nomination Systems and Legislator Ideology.” American Journal of Political Science 58 (2): 337–351.CrossRefGoogle Scholar
Poole, Keith, and Rosenthal, Howard. 1997. Congress: A Political-Economic History of Roll Call Voting. New York: Oxford University Press.Google Scholar
Poole, Keith T. 2007. “Changing Minds? Not in Congress!Public Choice 131: 435–451.CrossRefGoogle Scholar
Rodden, Jonathan, Shor, Boris, Warshaw, Christopher, Tausanovitch, Christopher, and McCarty, Nolan. 2014. “Geography and Polarization.” Working paper.
Shor, Boris, and McCarty, Nolan. 2011. “The Ideological Mapping of American Legislatures.” American Political Science Review 105 (3): 530–551.CrossRefGoogle Scholar
Tausanovitch, Chris, and Warshaw, Christopher. 2013. “Measuring Constituent Policy Preferences in Congress, State Legislatures, and Cities.” Journal of Politics 75 (2): 330–342.CrossRefGoogle Scholar
Theriault, Sean M. 2008. Party Polarization in Congress. Cambridge University Press.CrossRefGoogle Scholar
Voorheis, John. 2014. “State and Metropolitan Area Income Inequality in the United States: Trends and Determinants, 1968–2012.” Working paper.
Voorheis, John, Shor, Boris, and McCarty, Nolan. 2014. “State Legislative Political Polarization and Income Inequality in the United States, 1993–2013.” Working paper.
Wittman, Donald. 1983. “Candidate Motivation: A Synthesis of Alternative Theories.” American Political Science Review 77 (1): 142–157.CrossRefGoogle Scholar
Wright, Gerald C. and Schaffner, Brian F.. 2002. “The Influence of Party: Evidence from the State Legislatures.” The American Political Science Review 96 (2): 367–379.CrossRefGoogle Scholar

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