Informed voters are essential for government accountability, and social networks are an important avenue through which voters acquire political information. However, U.S. congressional districts do not need to align with social networks, potentially impacting how easily voters learn about their representatives. I study whether the alignment between district boundaries and social networks affects voter knowledge and turnout in congressional elections. Using Facebook's Social Connectedness Index and an event study design, I find that an increase in the share of friends living in the same district increases voters' knowledge about their representative. For example, a 10-percentage point (one standard deviation) increase in this share raises the probability that a voter knows their representative's party by 3.3 percentage points, a 5% increase over the mean. Additionally, a higher share of friends in the same district decreases voter abstention, and shifts campaign contributions towards in-district candidates. I use a model of information diffusion to simulate the share of informed voters under counterfactual district maps, creating a framework to evaluate the informational effects of proposed maps. These findings suggest that aligning political boundaries with social networks can enhance democratic engagement.
