"In this crucial, clarifying book, Pierson and Schickler systematically identify the institutional mechanisms that promote social divisions between Democrats and Republicans. Importantly, they also explain that today's polarization–while opening the door to democratic backsliding–may also be the only way to make progress toward multi-racial democracy. Indeed, they describe a political moment in which the United States teeters on the verge of either great progress or significant regression in the scope of its pluralism and democratic representation. Partisan Nation is a must-read for anyone hoping to understand the mechanisms behind the increasing extremism and animosity in American politics."–Lilliana Mason coauthor of "Radical American Partisanship"