The 1850s saw in America the breakdown of the Jacksonian party system in the North and the emergence of a new sectional party--the Republicans--that succeeded the Whigs in the nation's two-party system. This monumental work uses demographic, voting, and other statistical analysis as well as the more traditional methods and sources of political history to trace the realignment of American politics in the 1850s and the birth of the Republican party. Gienapp powerfully demonstrates that the organization of the Republican party was a difficult, complex, and lengthy process and explains why, even after an inauspicious beginning, it ultimately became a potent political force. The study also reveals the crucial role of ethnocultural factors in the collapse of the second party system and thoroughly analyzes the struggle between nativism and antislavery for political dominance in the North. The volume concludes with the decisive triumph of the Republican party over the rival American party in the 1856 presidential election. Far-reaching in scope yet detailed in analysis, this is the definitive work on the formation of the Republican party in antebellum America.