Malapportionment, Legislator Effort and the Representation of District Interests. Evidence from the Italian Senate

How does unequal representation affect policymaking? It is widely assumed that overrepresenteddistricts exert greater influence over policy, yet isolating the effects of representationfrom underlying district characteristics remains both theoretically and empirically challenging.I argue that increased representation can independently bias policymaking via twochannels: a mechanical effect, whereby increased representation raises a district’s probabilityof setting the agenda, and a behavioral effect, where legislators intensify their efforts dueto intra-district competition. To test this, I leverage the quasi-experimental setting createdby the electoral rule of the Italian Senate (1994-2006), which allowed districts with similarpopulation sizes to elect either one or two senators. Using a regression discontinuity designand comprehensive data on bill (co-)sponsorship, I find evidence supporting both channels.Examining policy outcomes, I do not find that unequal representation yields distributivebenefits, but I do find suggestive evidence of a broader legislative advantage.