美国各州间的政策扩散与极化
Policy Diffusion and Polarization across U.S. States
Review of Economic Studies · 2025 · [{"name": "Stefano DellaVigna", "affiliation": ["Berkeley College", "University of California, Berkeley"]}, {"name": "Woojin Kim", "affiliation": ["Stanford University"]}]
中文摘要
摘要 经济学家研究了众多州法律的影响，从福利规则到投票身份证件要求。然而，尽管已有如此多的政策评估，我们对政策扩散——即这些政策如何被引入并在州际间传播——又了解多少？我们基于一个涵盖过去七十年、包含 602 项美国州级政策的数据集，呈现一系列事实。第一，州能力的代理变量并不能预测创新新政策的更高可能性，但自 1990 年以来，州的政治倾向确实能预测引入党派性法律的更高可能性。第二，1950 年至 2000 年的政策扩散最能由邻近性预测——若邻近的州已经采纳某项政策，则该州更有可能采纳该政策——选民政策偏好的相似性同样具有预测力。第三，自 2000 年以来，政党一致性已成为政策扩散的最强预测因素，且采纳速度有所加快。学习模型与相关偏好模型能够解释较早时期的模式，但最近二十年的发现表明政党控制的作用急剧增强。我们由此得出结论：党派极化近来已成为政策采纳的一个关键因素，并可能导致州政策与选民偏好之间的匹配变差。
Abstract
Abstract Economists have studied the impact of numerous state laws, from welfare rules to voting ID requirements. Yet for all this policy evaluation, what do we know about policy diffusion—how these policies are introduced and spread from state to state? We present a series of facts based on a data set of 602 U.S. state policies spanning the past seven decades. First, proxies of state capacity do not predict a higher likelihood of innovating new policies, but the political leaning of the state does predict a higher likelihood of introducing partisan laws since 1990. Second, the diffusion of policies from 1950 to 2000 is best predicted by proximity—a state is more likely to adopt a policy if nearby states have already done so—as well as similarity in voter policy preferences. Third, since 2000, party alignment has become the strongest predictor of diffusion, and the speed of adoption has increased. Models of learning and correlated preferences can account for the earlier patterns, but the findings for the last two decades indicate a sharply increasing role of party control. We conclude that party polarization has emerged as a key factor recently for policy adoption, plausibly leading to a worse match between state policies and voter preferences.