Concerns about political polarization and threats to democratic ideals are on the rise in the US. The Authoritarian Divide takes on both of these issues by showing how authoritarian predispositions--desires for social conformity and in-group conformity--have influenced American political preferences, voting, and partisanship in recent decades. Voters have increasingly sorted into political parties based on their levels of authoritarianism, with higher levels tending toward the Republican Party and lower levels to Democratic. The authors reveal complexities in this trend, including the outsized effect on White Americans, the dependence on parties offering certain types of choices, and the different ways education level factors into the sorting process. Drawing from nationally representative samples, panel data, and experiments, the book demonstrates that authoritarianism has increasingly structured a wide range of attitudes and has become a growing influence on vote choice. The analysis carries crucial implications for partisan conflict and the future of American democracy.