Recent research has documented that lawmakers are more responsive to the views of the affluent than to the less well-off. This raises the important question of whether there are institutions that can limit unequal representation. We argue that labor unions play this role and we provide evidence from the contemporary U.S. House of Representatives. Our extensive dataset combines a novel measure of district-level union strength, drawn from 350,000 administrative records, with income-specific measures of constituency preferences based on 223,000 survey respondents matched to 27 roll-call votes. Exploiting within-district variation in preference polarization, within-state variation in union strength and rich data on confounds, our analysis rules out a host of alternative explanations. In contrast to the view that unions have become too weak or fragmented to matter, they significantly dampen unequal responsiveness: a standard deviation increase in union membership increases legislative responsiveness towards the poor by about 9 percentage points.
IAST working paper, n. 18-81, July 2018