Using methods of causal inference, computational social science and careful qualitative analysis, this thesis examines the roles that race and gender play in three key areas of modern American political life: political polarization, immigration policy and political participation.

In the first essay entitled "The Big Sort(s): Diversity, White Flight and Polarization in Neighborhoods and Cities,'' I develop the Migration-Flight-Polarization (MFP) hypothesis to explain how changes in diversity brought about by internal migration and immigration hold the key to understanding the connection between residential choice decisions and geographic polarization along partisan and ideological lines. Using an original agent-based modeling simulation and Hurricane Katrina evacuee data collected from schools and neighborhoods in Houston, Texas, I demonstrate that changes in diversity and "white flight'' responses to these changes are responsible for the growing partisan divide in Houston neighborhoods and the City of Houston as a whole.

My second essay entitled "Not in My Backyard: The Effect of Immigrant Race and Proximity on Immigration Policy Preferences,'' examines the extent to which immigrant race and proximity to a respondent informs immigration policy opinion. Using a survey experiment which employs blurry images of a fictional undocumented Mexican immigrant and respondent Internet Protocol addresses, I randomly manipulate immigrant skin tone and perceived distance between respondents and the immigrant. I find that the effect of race on immigration policy opinion depends upon the perceived distance between the immigrant and respondents. When respondents believe that the immigrant lives nearby, the darker immigrant elicits more anti-immigration responses to immigration policy questions. Conversely, when no immigrant location is provided, the darker immigrant elicits greater pro-immigration responses to the same questions. I also find that attitude polarization on immigration policy increases when respondents believe that the immigrant lives near them. These findings help explain the paradoxical divide between support for pro-immigration policies at the national level and anti-immigration policies at the state level.

My third essay with Morris Levy entitled "Estimating the Gender Penalty in the House: A Regression Discontinuity Approach,'' brings a novel regression discontinuity design to bear on the question of whether net voter bias against female candidates for office can help explain the limited growth of female election to the House of Representatives. Using house primary vote share as a forcing variable, we estimate the causal effect of a major party nominee's gender on that candidate's general election vote share. Our period of study encompasses all Congressional elections since 1982. Our findings suggest that female Republican candidates that barely win two-person House primaries against males receive a substantial boost in general election vote share. A similar effect among female winners of close Democratic primaries is not found.