The history of San Francisco from 1850 through 1900 identifies the active participation of citizens in communication, persuasion, and mobilization as the "public city," the site of American political and social change. Nineteenth-century Americans relied on the Roman and Enlightenment models of the "public sphere" as a forum for debate and self-government. Drawing on speeches, pamphlets, newspapers, and census and electoral data, the book reinterprets the city's turbulent history. Challenging decades of scholarship that treats urban politics as the expression of social-group experience and power, the author develops the opposite thesis that social-group identities of race, class, ethnicity, and gender were politically constructed in the public sphere in the process of mobilization and journalistic discourse. New methods of political mobilization unleashed by the Civil War resulted in the death of republican liberalism and birth of pluralist liberalism, and in the transformation from a political conception of society to a social conception of politics in the years from 1850 to 1900.