Social Networks and the Geography of Voting: A Spatial Econometric Approach

本文考察了社会网络的地理结构与选举结果之间的关系。它利用空间分析、计量经济学方法和关于不同地区人口之间社会联系密度的数据，为社会科学中的相关文献做出实证贡献。本文由引言、三个独立的实证章节和结语组成。这三个章节的共同主题是观察到，非本地的、甚至地理上相距遥远的社会关系可以在塑造本地投票行为方面发挥重要作用。在第一章中，我调查了社会接近与贸易相关的就业冲击对2016年英国是否留在欧盟公投中的投票选择的影响。看看国际领地3级(ITL3)地区的公投结果和英国选举研究中的个人投票数据，我考察了地区社会接近不同当地劳动力市场的冲击是否影响了对脱欧选项的支持。工具变量估计表明，社会溢出效应对投票行为的影响可与区域内暴露的效应相媲美，平均传播距离为74至102公里。在第二章中，我考察了美国全邮件投票政策在当地的推出对投票方式选择的社会溢出效应。结合北卡罗来纳州全体选民的个人行政记录和各州邮政编码制表地区(ZCTA)之间的社会联系数据，我考察了政策转换司法管辖区的社会联系份额如何影响2020年美国总统大选的邮件投票。差异差估计表明了积极的溢出效应，主要来自2000多公里外人口稠密的西部司法管辖区。在第三章中，我探讨了2020年美国总统大选中党派同质性的地理分布。我使用当地的莫兰指数来识别政治上亲同的ZCTA集群，并检查它们的特征。研究结果表明，虽然党派同质性的空间模式大致跟踪城乡连续体上的居住隔离，但在社会关系的相对密度和地理距离上存在显著的党派差异：倾向于民主党的同性恋地区很可能比倾向于同性恋的共和党地区在其他地方有更密集、更远的联系。总体而言，这篇论文为社会互动在选举中的作用及其与公共政策的联系提供了新的证据。

This thesis examines the relationship between the geographic structure of social networks and electoral outcomes. It draws on spatial analysis, econometric methods, and data on the density of social ties between the populations of different places to make empirical contributions to a body of related literatures in the social sciences. The thesis is comprised of an introduction, three independent empirical chapters, and a conclusion. The common theme uniting all three chapters is the observation that non-local, and even geographically distant social ties can play an important role in shaping local voting behaviour. In the first chapter, I investigate the effect of social proximity to trade-related employment shocks on vote choice in the 2016 UK EU membership referendum. Looking at referendum results in International Territorial Level 3 (ITL3) regions and individual-level voting data from the British Election Study, I examine whether regional social proximity to shocks in different local labour markets affected support for the Leave option. Instrumental variable estimates suggest that social spillover effects on voting behaviour are comparable to those of within-region exposure and travel an average distance of 74 to 102 kilometres. In the second chapter, I examine social spillovers on choice of voting method from local rollouts of all-mail voting policy in the United States. Combining individual-level administrative records on the entire electorate of North Carolina and data on the social ties between zip code tabulation areas (ZCTAs) across states, I look at how the share of social ties in policy-switching jurisdictions affected mail voting in the 2020 US presidential election. Difference-in-differences estimates are indicative of positive spillover effects, primarily originating from populous Western jurisdictions located over 2,000 kilometres away. In the third chapter, I explore the geography of partisan homophily in the 2020 US presidential election. I use the local Moran index to identify clusters of politically homophilous ZCTAs and examine their characteristics. The findings suggest that while spatial patterns of partisan homophily broadly track residential segregation along the urban-rural continuum, there are notable partisan differences in the relative density and geographic distance of social ties: homophilous Democratic-leaning areas are likely to have denser and more distant ties elsewhere than homophilous Republican-leaning areas. Overall, the thesis contributes new evidence on the role of social interactions in elections and its links to public policy.