I apply the novel RD Aggregation method to assess the political impact of US trade unions. The method enables the aggregation of several discontinuity events–close unionization elections–into a commuting zone level shock that measures the unions’ ”Luck” in each zone in each period. Using this methodology, I find that, on average, a newly unionized worker is worth 2 new votes for the Democratic party candidate in the following presidential elections and that unions shift local congressmen to the left. Further analysis suggests that the significant effects partly stem from increased campaign contributions, strategic political resource allocation by unions in areas with new members, and direct impact on union members.

We document that during 1992-2019, the election of American female state legislators increased the local abortion rate. To establish causality, we adopt a close-elections approach. Specifically, in a methodological contribution, we implement the novel Regression Discontinuity Aggregation method. The documented effect is driven by Democratic women, who mold reproductive regulation. In contrast, Democrat men have no effect. We show the gender divergence within the Democratic party stems not from women viewing abortions differently than men but from them prioritizing reproductive issues. We conclude that in competitive systems, politicians’ individual preferences may alter legislative behavior primarily by determining how they allocate political resources.

This paper studies how academic fields shape students’ political attitudes. Using panel surveys of roughly 300,000 U.S. college students who enrolled between 1990 and 2015, we compare students across majors, conditioning on pre-college political attitudes and major-related preferences. The estimated effects are substantial: relative to the natural sciences, social sciences and humanities shift students left, while economics and business shift them right, with the largest effects on economic policy positions. Several findings support a causal interpretation. The estimates are robust to conservative sensitivity analyses, and the controls absorb nearly all the bias attributable to observed demographic and behavioral characteristics. Two complementary analyses exploiting supply-side variation in field availability yield consistent results. The effects also extend to related behaviors and priorities: social sciences and humanities increase political activism, whereas economics and business increase the importance students place on financial success. The evidence suggests that the academic environment, rather than peers’ socialization or expected earnings, is the main mechanism. Finally, field choice contributes to political fragmentation because students select majors that align with their preexisting attitudes.

Abstract We extend the regression discontinuity (RD) design to settings where each unit's treatment status is an average or aggregate across multiple discontinuity events. Such situations arise in many studies where the outcome is measured at a higher level of spatial or temporal aggregation (e.g., by state with district-level discontinuities) or when spillovers from discontinuity events are of interest. We propose two novel estimation procedures — one at the level at which the outcome is measured and the other in the sample of discontinuities — and show that both identify a local average causal effect under continuity assumptions similar to those of standard RD designs. We apply these ideas to study the effect of unionization on inequality in the United States. Using credible variation from close unionization elections at the establishment level, we show that a higher rate of newly unionized workers in a state-by-industry cell reduces wage inequality within the cell. [A new draft is available upon request.]