American Gridlock brings together the country’s preeminent experts on the causes, characteristics, and consequences of partisan polarization in US politics and government, with each chapter presenting original scholarship and novel data. This book is the first to combine research on all facets of polarization, among the public (both voters and activists), in our federal institutions (Congress, the presidency, and the Supreme Court), at the state level, and in the media. Each chapter includes a bullet-point summary of its main argument and conclusions, and is written in clear prose that highlights the substantive implications of polarization for representation and policy-making. Authors examine polarization with an array of current and historical data, including public opinion surveys, electoral and legislative and congressional data, experimental data, and content analyses of media outlets. American Gridlock’s theoretical and empirical depth distinguishes it from any other volume on polarization.