Written by leading historians of the mid–nineteenth century United States, this book focuses on the continental dimensions of the U.S. Civil War. It joins a growing body of scholarship that seeks to understand the place of America’s mid-nineteenth-century crisis in the broader sweep of world history. However, unlike other studies that have pursued the Civil War’s connections with Europe and the Caribbean, this volume focuses on North America, particularly Mexico, British Canada, and sovereign indigenous states in the West. As the United States went through its Civil War and Reconstruction, Mexico endured its own civil war and then waged a four-year campaign to expel a French-imposed monarch. Meanwhile, Britain’s North American colonies were in complex and contested negotiations that culminated in confederation in 1867. In the West, indigenous nations faced an onslaught of settlers and soldiers seeking to conquer their lands for the United States. Yet despite this synchronicity, mainstream histories of the Civil War mostly ignore its connections to the political upheaval occurring elsewhere in North America. By reading North America into the history of the Civil War, this volume shows how battles over sovereignty in neighboring states became enmeshed with the fratricidal conflict in the United States. Its contributors explore these entangled histories in studies ranging from African Americans fleeing U.S. slavery by emigrating to Mexico to Confederate privateers finding allies in Halifax, Nova Scotia. This continental perspective highlights the uncertainty of the period when the fate of old nations and possibilities for new ones were truly up for grabs.