Effectiveness of connected legislators

Important work has been done to measure legislative effectiveness in the U.S. Congress and to explain the individual characteristics that drive it. Much less attention, however, has been devoted to study the extent to which legislative effectiveness depends on the legislators' social connections. We address this issue with a new model of legislative effectiveness that formalizes the role of social connections, and we test its predictions using the network of cosponsorship links in the 109th-113th Congresses. We propose a new empirical strategy that addresses network endogeneity by implementing a two-step Heckman correction based on an original instrument: the legislators' alumni connections. We find that social connections are a significant determinant of legislative effectiveness. We also study the influence of legislators' characteristics in shaping the network effects. In doing so, we provide new insights into how social connectedness interacts with factors such as seniority, partisanship, and legislative leadership in determining legislators' effectiveness.