Publications

Shor, Boris. 2025. “Are State Legislative Leaders Moderates?” Legislative Studies Quarterly 50(4) [ABSTRACT-START]Spatial models of legislative organization predict that elected leaders will be moderates with respect to their constituency, the party caucus. However, empirical studies of leader positioning in Congress find mixed evidence that this is the case. This paper expands the analysis to state legislatures, using an original dataset of 2056 top chamber and party leaders in 50 states from 1999 to 2023. Simulations reveal that state legislative leaders are consistently moderate relative to their caucus. Furthermore, while Democratic leaders consistently occupy the moderate left side of their caucus, Republican leaders do not show the same pattern, with some even positioned to the left of their caucus median. Beyond this overall pattern, there is substantial variation in leader-caucus ideological divergence. The analysis shows that increasingly distinct and homogeneous majority parties—fulfilling the conditions of conditional party government theory—are consistently associated with leader moderation. However, this effect is stronger for Republicans than for Democrats, which is inconsistent with the theory’s predictions of party symmetry. Finally, using a new dataset on majority party roll rates, the spatial divergence of majority party leaders from their caucuses is found to lead to significant failures of agenda control, with a substantial increase in majority party rolls for moderate Republicans but not for Democrats. This finding contradicts the predictions of party cartel theory, which suggests no differences in agenda control based on leader ideology or party. The evidence consistently shows substantial asymmetry between Republican and Democratic leaders.[ABSTRACT-END].
Shor, Boris, and Michael Kistner. 2024. “Comparing Leviathans: Agenda Influence in State Legislatures, 2011 to 2023.” Journal of Political Institutions and Political Economy 4(4): 551–76 [ABSTRACT-START]An extensive literature argues that majority parties function as leviathans (or cartels) that control the agenda, deciding which policies will advance to a vote and which policies will not. However, most studies focus on only a single institution, precluding the development and testing of generalizable theories of agenda influence. We address this gap by introducing new data on agenda control outcomes (both negative and positive) spanning the entirety of state legislatures over a thirteen year period. Using this data, we highlight previously unnoticed patterns in agenda influence, most notably the presence of stark partisan asymmetries. Republican majorities get rolled at approximately four times the rate of Democratic majorities, a finding that holds both across and within institutions. More broadly, we find consistent evidence of greater agenda influence for Democratic majorities, suggesting a need for new theory to explain these differences.[ABSTRACT-END].
Anderson, Soren T, Ioana Marinescu, and Boris Shor. 2023. “Can Pigou at the Polls Stop Us Melting the Poles?” Journal of the Association of Environmental and Resource Economists 10(4). National Bureau of Economic Research [ABSTRACT-START]Economists recommend Pigouvian taxes as the most efficient way to fight climate change. Yet, carbon taxes are difficult to implement politically. To understand why, we study Washington State’s two failed carbon tax referendums from 2016 and 2018—the first such votes in the United States. We find that average voters’ opposition to the carbon tax can partly be explained by the anticipation of higher energy costs. Meanwhile, ideology—as measured by voting on other initiatives—explains 90[ABSTRACT-END].
Shor, Boris, and Nolan McCarty. 2022. “Two Decades of Polarization in American State Legislatures.” Journal of Political Institutions and Political Economy 3(3-4): 343–70 [ABSTRACT-START]One of the most robust findings in American politics is the decades-long trends in the level of elite partisan polarization. Among the most consequential of these trends has been that of state legislators. Polarization among these officials has had significant ramifications for political representation, policy making, and the workings of the US federal system. In this paper, we update the analysis of Shor and McCarty (2011) with comprehensive data from 1996 to 2020 for the state legislatures of all fifty states. We extend the analysis of state legislative polarization back to 1977 for a select set of states. These updates reinforce our earlier findings about the pervasiveness of polarization and its links to national trends. The new data also highlight features of polarization that appear unique to the states. While the polarization US Congress has been characterized by an asymmetric pattern of GOP movement to the right, the predominant asymmetry in the states is one characterized by Democratic movement to the left. Additionally, we discuss the burgeoning literature on evaluating the causes of polarization using our measures as well that identifying its consequences.[ABSTRACT-END].
Kousser, Thad, Justin H. Phillips, and Boris Shor. 2018. “Reform and Representation: Assessing California’s Top-Two Primary and Redistricting Commission.” Political Science Research and Methods 6(4): 809–27 [ABSTRACT-START]Can electoral reforms such as an independent redistricting commission and the top-two primary create conditions that lead to better legislative representation? We explore this question by presenting a new method for measuring a key indicator of representation—the congruence between a legislator’s ideological position and the average position of her district’s voters. Our novel approach combines two methods: the joint classification of voters and political candidates on the same ideological scale, along with multilevel regression and post-stratification to estimate the position of the average voter across many districts in multiple elections. After validating our approach, we use it to study the recent impact of reforms in California, showing that they did not bring their hoped-for effects.[ABSTRACT-END].
McCarty, Nolan, Jonathan Rodden, Boris Shor, Christopher Tausanovitch, and Christopher Warshaw. 2018. “Geography, Uncertainty, and Polarization.” Political Science Research and Methods 7(4): 775–94 [ABSTRACT-START]Using new data on roll-call voting of US state legislators and public opinion in their districts, we explain how ideological polarization of voters within districts can lead to legislative polarization. In so-called “moderate” districts that switch hands between parties, legislative behavior is shaped by the fact that voters are often quite heterogeneous: the ideological distance between Democrats and Republicans within these districts is often greater than the distance between liberal cities and conservative rural areas. We root this intuition in a formal model that associates intradistrict ideological heterogeneity with uncertainty about the ideological location of the median voter. We then demonstrate that among districts with similar median voter ideologies, the difference in legislative behavior between Democratic and Republican state legislators is greater in more ideologically heterogeneous districts. Our findings suggest that accounting for the subtleties of political geography can help explain the coexistence of polarized legislators and a mass public that appears to contain many moderates.c[ABSTRACT-END].
McGhee, Eric, and Boris Shor. 2018. “Has the Top Two Primary Elected More Moderates?” Perspectives on Politics 15(4): 1053–66 [ABSTRACT-START]Party polarization is perhaps the most significant political trend of the past several decades of American politics. Many observers have pinned hopes on institutional reforms to reinvigorate the political center. The Top Two primary is one of the most interesting and closely-watched of these reforms: a radically open primary system that removes much of the formal role for parties in the primary election and even allows for two candidates of the same party to face each other in the fall. Here we leverage the adoption of the Top Two in California and Washington to explore the reform’s effects on legislator behavior. We find an inconsistent effect since the reform was adopted in these two states. The evidence for post-reform moderation is stronger in California than in Washington, but some of this stronger effect appears to stem from a contemporaneous policy change—district lines drawn by an independent redistricting commission—while still more might have emerged from a change in term limits that was also adopted at the same time. The results validate some claims made by reformers, but question others, and their magnitude casts some doubt on the potential for institutions to reverse the polarization trend.[ABSTRACT-END].
Shor, Boris. 2018. “Ideology, Party and Opinion: Explaining Individual Legislator ACA Implementation Votes in the States.” State Politics and Policy Quarterly 18(4): 371–94 [ABSTRACT-START]Why do state legislators vote the way they do? Which influence is predominant: ideology, party, or public opinion? The implementation votes surrounding the Affordable Care Act (ACA) provides a unique setting to examine this question, as they make all three considerations highly salient. State roll call votes on ACA implementation were sometimes polarized and sometimes unexpectedly bipartisan. What accounts for the heterogeneity in individual legislator behavior on bills implementing the ACA at the state level? Using new data on legislator ideology and votes from 2011–2015, I show evidence that legislator ideology was by far the most important predictor of voting on implementation votes, far more so than legislator party or public opinion. Moreover, I show the influence of ideology is heterogeneous by issue area and bill.[ABSTRACT-END].
Butler, Daniel M, Craig Volden, Adam Dynes, and Boris Shor. 2017. “Ideology, Learning, and Policy Diffusion: Experimental Evidence.” American Journal of Political Science 61(1): 37–49 [ABSTRACT-START]We introduce experimental research design to the study of policy diffusion in order to better understand how political ideology affects policymakers’ willingness to learn from one another’s experiences. Our two experiments–embedded in national surveys of U.S. municipal officials–expose local policymakers to vignettes describing the zoning and home foreclosure policies of other cities, offering opportunities to learn more. We find that: (1) policymakers who are ideologically predisposed against the described policy are relatively unwilling to learn from others, but (2) such ideological biases can be overcome with an emphasis on the policy’s success or on its adoption by co-partisans in other communities. We also find a similar partisan-based bias among traditional ideological supporters, who are less willing to learn from those in the opposing party. The experimental approach offered here provides numerous new opportunities for scholars of policy diffusion.[ABSTRACT-END].
Masket, Seth E, and Boris Shor. 2015. “Polarization Without Parties: The Rise of Legislative Partisanship in Nebraska’s Unicameral Legislature.” State Politics & Policy Quarterly 15(1): 67–90 [ABSTRACT-START]Despite a long history of nonpartisanship, the Nebraska state legislature has polarized rapidly within the past decade. Using interviews and campaign finance records, we examine politics in the modern Unicam to investigate nonpartisan polarization. We find that newly instituted term limits created opportunities for the state’s political parties to recruit and finance candidates in an increasingly partisan fashion. Social network analysis suggests that there is a growing level of structure to campaign donations, with political elites increasingly less likely to contribute across party lines. The results offer a compelling example of parties overcoming institutions designed to eliminate them.[ABSTRACT-END].
Shor, Boris. 2015a. “How US States Are Polarized and Getting More Polarized.” In Political Polarization in American Politics. Bloomsbury.
Shor, Boris. 2015b. “State Legislative Polarization in America’s State Legislatures.” In American Gridlock: The Sources, Character, and Impact of Political Polarization. Cambridge University Press.
Gray, Virginia, John Cluverius, Jeffrey Harden, Boris Shor, and David Lowery. 2014. “Party Competition, Party Polarization, and the Changing Demand for Lobbying in the American States.” American Politics Research 43(2) [ABSTRACT-START]Interest system density influences internal dynamics within interest organizations, how they lobby, and policy conditions. But how do political conditions influence interest system density? How does politics create demand for interest representation? We examine these questions by assessing how legislative party competition and ideological distance between parties in state legislatures affect the number of lobby groups. After stating our theoretical expectations, we examine 1997 and 2007 data on legislative competition and party polarization to assess their influence on system density. We find mixed results: Whereas politics slightly influenced the structuring of nonprofit interest communities, they seem to have not affected the structuring of for-profit interest communities or interest communities as a whole.[ABSTRACT-END].
McGhee, Eric, Seth E. Masket, Boris Shor, Steven Rogers, and Nolan M. McCarty. 2014. “A Primary Cause of Partisanship? Nomination Systems and Legislator Ideology.” American Journal of Political Science 58(2): 337–51 [ABSTRACT-START]Many theoretical and empirical accounts of representation argue that primary elections are a polarizing influence. Likewise, many reformers advocate opening party nominations to nonmembers as a way of increasing the number of moderate elected officials. Data and measurement constraints, however, have limited the range of empirical tests of this argument. We marry a unique new data set of state legislator ideal points to a detailed accounting of primary systems in the United States to gauge the effect of primary systems on polarization. We find that the openness of a primary election has little, if any, effect on the extremism of the politicians it produces.[ABSTRACT-END].
Feller, Avi, Andrew Gelman, and Boris Shor. 2012. “Red State-Blue State Divisions in the 2012 Presidential Election.” The Forum 10(4): 127–31 [ABSTRACT-START]The so-called “red/blue paradox” is that rich individuals are more likely to vote Republican but rich states are more likely to support the Democrats. Previous research argued that this seeming paradox could be explained by comparing rich and poor voters within each state – the difference in the Republican vote share between rich and poor voters was much larger in low-income, conservative, middle-American states like Mississippi than in high-income, liberal, coastal states like Connecticut. We use exit poll and other survey data to assess whether this was still the case for the 2012 Presidential election. Based on this preliminary analysis, we find that, while the red/blue paradox is still strong, the explanation offered by Gelman et al. no longer appears to hold. We explore several empirical patterns from this election and suggest possible avenues for resolving the questions posed by the new data.[ABSTRACT-END].
Shor, Boris, and Nolan McCarty. 2011. “The Ideological Mapping of American Legislatures.” American Political Science Review 105(3): 530–51 [ABSTRACT-START]The development and elaboration of the spatial theory of voting has contributed greatly to the study of legislative decision making and elections. Statistical models that estimate the spatial locations of individual decision-makers have made a key contribution to this success. Spatial models have been estimated for the U.S. Congress, the Supreme Court, U.S. presidents, a large number of non-U.S. legislatures, and supranational organizations. Yet one potentially fruitful laboratory for testing spatial theories, the individual U.S. states, has remained relatively unexploited, for two reasons. First, state legislative roll call data have not yet been systematically collected for all states over time. Second, because ideal point models are based on latent scales, comparisons of ideal points across states or even between chambers within a state are difficult. This article reports substantial progress on both fronts. First, we have obtained the roll call voting data for all state legislatures from the mid-1990s onward. Second, we exploit a recurring survey of state legislative candidates to allow comparisons across time, chambers, and states as well as with the U.S. Congress. The resulting mapping of America’s state legislatures has great potential to address numerous questions not only about state politics and policymaking, but also about legislative politics in general.[ABSTRACT-END].
Gelman, Andrew, David Park, Boris Shor, and Jeronmio Cortina. 2010. Red State, Blue State, Rich State, Poor State: Why Americans Vote the Way They Do. Princeton University Press [ABSTRACT-START]On the night of the 2000 presidential election, Americans watched on television as polling results divided the nation’s map into red and blue states. Since then the color divide has become symbolic of a culture war that thrives on stereotypes–pickup-driving red-state Republicans who vote based on God, guns, and gays; and elitist blue-state Democrats woefully out of touch with heartland values. With wit and prodigious number crunching, the authors debunk these and other political myths.[ABSTRACT-END].
Shor, Boris, Christopher Berry, and Nolan McCarty. 2010. “A Bridge to Somewhere: Mapping State and Congressional Ideology on a Cross-Institutional Common Space.” Legislative Studies Quarterly 35(3): 417–48 [ABSTRACT-START]Researchers face two major problems when applying ideal point estimation techniques to state legislatures. First, longitudinal roll-call data are scarce. Second, even when such data exist, scaling ideal points within a single state is an inadequate approach. No comparisons can be made between these estimates and those for other state legislatures or for Congress. Our project provides a solution. We exploit a new comparative dataset of state legislative roll calls to generate ideal points for legislators. Taking advantage of the fact that state legislators sometimes go on to serve in Congress, we create a common ideological scale. Using these bridge actors, we estimate state legislative ideal points in congressional common space for 11 states. We present our results and illustrate how these scores can be used to address important topics in state and legislative politics.[ABSTRACT-END].
Shor, Boris, Joseph Bafumi, Luke Keele, and David Park. 2007. “A Bayesian Multilevel Modeling Approach to Time-Series Cross-Sectional Data.” Political Analysis 15(2): 165–81 [ABSTRACT-START]The analysis of time-series cross-sectional (TSCS) data has become increasingly popular in political science. Meanwhile, political scientists are also becoming more interested in the use of multilevel models (MLM). However, little work exists to understand the benefits of multilevel modeling when applied to TSCS data. We employ Monte Carlo simulations to benchmark the performance of a Bayesian multilevel model for TSCS data. We find that the MLM performs as well or better than other common estimators for such data. Most importantly, the MLM is more general and offers researchers additional advantages.[ABSTRACT-END].
Gelman, Andrew, Boris Shor, Bafumi Joseph, and David Park. 2007. “Rich State, Poor State, Red State, Blue State: What’s the Matter with Connecticut?” Quarterly Journal of Political Science 2(4): 345–67 [ABSTRACT-START]For decades, the Democrats have been viewed as the party of the poor, with the Republicans representing the rich. Recent presidential elections, however, have shown a reverse pattern, with Democrats performing well in the richer blue states in the northeast and coasts, and Republicans dominating in the red states in the middle of the country and the south. Through multilevel modeling of individuallevel survey data and county- and state-level demographic and electoral data, we reconcile these patterns.Furthermore, we find that income matters more in red America than in blue America. In poor states, rich people are much more likely than poor people to vote for the Republican presidential candidate, but in rich states (such as Connecticut), income has a very low correlation with vote preference.Key methods used in this research are: (1) plots of repeated cross-sectional analyses, (2) varying-intercept, varying-slope multilevel models, and (3) a graph that simultaneously shows within-group and between-group patterns in a multilevel model. These statistical tools help us understand patterns of variation within and between states in a way that would not be possible from classical regressions or by looking at tables of coefficient estimates.[ABSTRACT-END].