What Drives Mass Polarization in the United States?

Academic studies on political polarization in the American public have coalesced into three fundamentally related yet distinct bodies of literature on ideological, partisan, and affective polarization. While each of these areas have contributed to a greater understanding of what divides the American polity, they have largely developed as separate lines of research and interact less than might be expected given their shared central questions of political behavior and public opinion. This thesis unites these major dimensions, aiming to assemble a more complete illustration of the central driving influences of polarization in the American public. Following an analysis of scholarly literature ranging from foundational to the most recent contributions, I draw upon a single, large-scale dataset (ANES) to directly evaluate the evidence of mass polarization over several decades, highlighting the recent accelerated change in some of these measures. However, this work is cautious to not overstate the current political cleavage in the U.S., noting how misperceptions and overestimations of the state of mass polarization may contribute to its exacerbation.