Media markets, special interests, and voters

This paper examines the role of mass media in countering special interest group influence. I use the concentration of campaign contributions from Political Action Committees to proxy for special interests' capture of US Senate candidates from 1980 to 2002, and compare the reaction of voters to increases in concentration in two different types of media markets: in-state media markets and out-of-state media markets. Unlike in-state media markets, out-of-state markets focus on neighboring states' politics and elections. Thus, if citizens punish political capture, increases in concentration of special interest contributions to a particular candidate should reduce his vote share in in-state counties relative to the out-of-state counties, where the candidate receives less coverage. I find that a one-standard deviation increase in concentration of special interest contributions to incumbents reduces their vote share by about 0.5 to 1.5percentage points in in-state counties relative to the out-of-state counties. Robustness checks suggest that these results are not driven by omitted Senator characteristics or by differences between in-state and out-of-state counties along dimensions other than the media environment.