ELECTORAL INSTITUTIONS, HOMETOWNS, AND FAVORED MINORITIESEvidence from Japanese Electoral ReformsBy SHIGEO HIRANO*I. INTRODUCTIONWHY do legislators choose to represent particular constituencies and why do they support particular policies? The conventional wisdom in the literature is that these decisions are infl uenced by the incentives associated with particular electoral institutions.1 However, despite the extensive literature linking electoral institutions and legis-lators’ behaviors, there are relatively few empirical studies that clearly identify the infl uence of electoral institutions on the constituencies leg-islators choose to represent and the policies they choose to support. Some studies of recent electoral reforms fi nd little difference between candidates’ electioneering behaviors before and after changes in various World Politics 58 (October 2006), 51–82* I thank James E. Alt, Jasjeet S. Sekhon, James M. Snyder, Jr., Scott Ashworth, Dawn M. Bran-cati, John D. Huber, Christina Davis, Yoshiro Miwa, Susan J. Pharr, Frances Rosenbluth, and Ethan Scheiner for valuable comments and advice. I also thank seminar participants at Harvard, Princeton, NYU, Notre Dame, Cornell, UC Davis, Washington University, and the University of Tokyo for help-ful comments on an earlier version of this paper. I thank the Center for Basic Research in the Social Sciences, the Harvard Reischauer Institute, the Center for the Study of Democratic Politics, and the NYU Politics Department for fi nancial and institutional support.1 See, for example, Barry Ames, “Electoral Strategy under Open-List Proportional Representa-tion,” American Journal of Political Science 88 (March 1995); Bruce Cain, John Ferejohn, and Mor-ris Fiorina, The Personal Vote: Constituency Service and Electoral Independence (Cambridge: Harvard University Press, 1987); John M. Carey and Matthew S. Shugart, “Incentives to Cultivate a Personal Vote: A Rank Ordering of Electoral Formulas,” Electoral Studies 14 (December 1995); Gary W. Cox, “Electoral Equilibria under Alternative Voting Institutions,” American Journal of Political Science 31 (February 1987); idem, “Centripetal and Centrifugal Incentives in Electoral Systems,” American Jour-nal of Political Science 34 (November 1990); Alessandro Lizzeri and Nicola Persico, “The Provision of Public Goods under Alternative Electoral Incentives,” American Economic Review 91 (March 2001); Roger B. Myerson,“Incentives to Cultivate Favored Minorities under Alternative Electoral Systems,” American Political Science Review 87 (December 1993); and Robert Pekkanen, Benjamin Nyblade, and Ellis S. Krauss, “Electoral Incentives in Mixed-Member Systems: Party Posts and Zombie Politicians in Japan,” American Political Science Review 100 (May 2006).electoral systems, raising questions about the impact of electoral insti-tutions on candidate behavior.2In this article I provide evidence that electoral institutions do affect the relationship between legislators and specifi c constituencies within electoral districts. The evidence is consistent with the logic developed in a formal theoretical model by Roger B. Myerson.3 This model shows that the multimember single nontransferable vote (SNTV) system pro-vides incentives for legislative candidates to appeal to narrow subcon-stituencies by reducing the vote-share threshold that candidates need to secure a legislative seat. According to Myerson’s model, if a candidate appeals to broad cross-sections of a multimember district’s electorate, she will leave herself vulnerable to challengers who can concentrate their efforts on the minimal subset of the constituency necessary to win a seat. Thus, candidates in single-member districts (SMD) are expected to represent a broader cross-section of their district constituents than are candidates in multimember districts, which is what the fi ndings in this article demonstrate.In addition to providing evidence consistent with the logic of the Myerson model, this article also illustrates the impact electoral insti-tutions can have on geographic patterns of representation. Although the geographic concentration of legislators’ electoral support has been observed in various multimember district systems in Europe, Latin America, and Asia,4 there has been little systematic evidence directly linking the vote concentration to the electoral institutions. The evi-dence in this article shows that the high geographic concentration of legislators’ electoral support was closely tied to Japan’s multimember district system.To identify the effect of the multimember SNTV and SMD electoral institutions on representation, I exploit two political reforms that oc-curred in Japan. In 1994 the electoral system for the Japanese Lower House of the Diet changed from a multimember SNTV system to a 2 See, for example, Brian F. Crisp and Rachel E. Ingall, “Institutional Engineering and the Nature of Representation: Mapping the Effects of Electoral Reform in Colombia,” American Journal of Politi-cal Science 46 (October 2002); Hideo Otake, How Electoral Reform Boomeranged (Tokyo: Japan Center for International Exchange, 1998); and Margaret McKean and Ethan Scheiner, “Japan’s New Electoral System: La Plus Ça Change . . . ,” Electoral Studies 19 (December 2000).3 Myerson (fn. 1). Gary W. Cox’s models develop a similar logic for relationships between electoral institutions and dispersion of candidates’ policy positions along a unidimensional policy space. See Cox (fn. 1, 1990).4 See, for example, Barry Ames, Deadlock of Democracy (Ann Arbor: University of Michigan Press, 2001); Crisp and Ingall (fn. 2); Brian F. Crisp and Scott Desposato, “Constituency Building in Multi-member Districts: Collusion or Confl ict?” Journal of Politics 66 (February 2004); Gerald Curtis, Elec-tion Campaigning Japanese Style (New York: Columbia University Press, 1971); Paul M. Sacks, The Donegal Mafi a: An Irish Political Machine (New Haven: Yale University Press, 1976).52 WORLD POLITICSmixed-member majoritarian system (MMM) with an SMD component and a proportional representation component. In 1925 the electoral system changed from a predominantly SMD system to a multimember SNTV system.5Japan is a good case for testing whether these electoral institutions affect the types of constituencies candidates represent. Japanese Lower House representatives are known to have appealed to geographically defi ned