I am a PhD Candidate in Government at Harvard University studying political behavior in American politics. In particular, I am interested in how political geography and group identity structure political behavior. My dissertation investigates the behavioral consequences of geographic partisan polarization, with specific focus on how this polarization is self-reinforcing: how living in increasingly homogeneous partisan environments influences voters’ political affiliations. To this end, I develop data on the partisan residential exposure of every voter in the United States over the past decade, leveraging precise information on each voter's residential location, partisan affiliation, and political behavior. With these data I present new evidence on the extent and causes of partisan sorting in the United States and test new theories of how where Democrats and Republicans live in relation to one another influences political behavior.