The author investigates the idea of national union in the United States. For much of the period between the colonial era and the late 19th century, he shows, "union" was the principal rhetorical means by which Americans expressed shared ideals and a common identity without invoking strong nationalism or centralized governance. Through his exploration of how Americans once succeeded in uniting a diverse and fragmented citizenry, Rogan Kersh revives a long-forgotten source of US national identity. Why and how did Americans perceive themselves as one people from the early history of the republic? How did African-Americans and others at the margins of US civic culture apply this concept of union? Why did the term disappear from the vernacular after the 1880s? In his search for answers, Kersh employs a wide range of methods, including political-theory analysis of writings by James Madison, Frederick Douglass and Abraham Lincoln, and empirical analysis drawing on his own database of American newspapers. One particular development he highlights is the strong resurgence of union feelings among Southerners - including prominent former secessionists - after the Civil War. As well as offering insights into American political history, especially the rise of nationalism and federalism, the author's retracing of the religious, insitutional and other themes colouring the development of unionist thought unveils knowledge about the origination and transmittal of ideas in a polity.