Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Political Science

Major Professor

Ian Down

Committee Members

Jana Morgan, Nathan J. Kelly, Kyung Joon Han, Jon Shefner


Previous research on the determinants of economic inequality in the wealthy democracies has found that differences in the size and constitution of labor unions accounts for much of the cross-national and over time variation in economic inequality. Despite numerous theoretical and empirical reasons to suppose the contrary, most of this research assumes that the union effect on economic inequality is independent of the particular socio-economic and political environment unions are situated within and the types of workers actually unionized. The broad purpose of this dissertation is to push back against these assumptions and examine whether the union effect on economic inequality is conditioned by certain factors external and internal to unions. This is done through consideration of the four processes by which unions impact economic inequality; which I label the employer, intra-union, insider, and political mechanisms. In particular, I argue that the level of unionization conditions the political mechanism by providing (dis)incentives for parties of the left and right to respond to union member preferences for government action to reduce economic inequalities (chapter 2); that increasing exposure to the world economy conditions the employer, intra-union, and insider mechanisms by reducing the ability and willingness of lower-paid union workers to extract wage gains from their employers (chapter 3); and that market institution and welfare state regimes indirectly condition the employer, intra-union, and insider mechanisms for female and male union workers by generating particular forms and levels of vertical gender occupational segregation within unions (chapter 4). The empirical analyses focus on between 8 and 16 wealthy democracies (depending on data availability) over the final decades of the twentieth century and the first decade of the twenty-first century. The evidence presented suggests that we cannot understand the totality of the union effect on economic inequality - or on any other socio-economic outcome - without considering each of the four mechanisms by which unions impact economic inequality, the many and varied ways these mechanisms are expressed, and how these mechanisms interact within particular contexts.

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