The Micro-Geography of Persuasion: Randomized Peer Exposure and Legislative Outcomes

We find that randomly assigned peers play a sizable and unique role in shaping political economy. Closely seated, and exogenously assigned, US Senate peers have a significant impact on Congressional voting, shifting votes by 11.9 percentage points (t=7.34). Physical distance is the largest and most consistent of any characteristic outside of party or state in impacting voting behavior. The distance effect is concentrated in the closest peers, existing for up to 19.6 feet on the Senate floor, then dissipating. Close peers additionally increase the probability of aisle-crossing (voting with the opposite party), with the aisle-crossing impact being roughly eight times larger on the final votes on bills. We then utilize a state-of-the-art AI-enhanced computer vision model based on real-time interactions using CSPAN video data at every 10-second interval amongst Congressional members. Using these observed interactions, we find that face-to-face interactions are associated with significant impacts on immediately pending votes. The interactions are largely driven by distance, with aisle-seated Senators from both parties being amongst the most likely to engage in face-to-face interactions across party lines. By conducting counterfactuals through randomized Senate seating, 59 consequential bills would have switched outcomes over our 30-year sample period.