I have written several books and articles on the dynamics of secession historically and globally. In an earlier book, Secession and the Sovereignty Game: Strategy and Tactics for Aspiring Nations (2021), I conducted interviews with over a dozen secessionist movements in places like Catalonia, West Papua, and Northern Cyprus. Although my interest in this topic began as a graduate student, I was drawn to the subject as a global phenomenon and not as a particularly American one.The reason I decided to write The Disunited States is that I began to witness a growing interest in American secession. I understand, of course, the polarization is feeding that interest. But those who advocate for secession in America are generally unaware of the difficult process through which secessionist regions can join the community of sovereign states. For instance, there are complex recognition practices and a general agreement that secessionists cannot just unilaterally choose to become a country. Their home state needs to agree.Most secessionists, not just in America but globally, think that wishful thinking and a good argument can win them independence. But the realities of secession are far more complicated. Importantly, it is understandable that secessionists rarely know how the process works. State birth via secession is not a regular occurrence, and there is no set of laws and guidelines for how it should be conducted. It is a process that typically transcends law, one that becomes deeply political and prone to conflict.I do not offer a solution to polarization in this book. Instead, I bring to the table an expertise on how secession works around the world. I think that knowledge is currently absent in the developing conversation about secession as a solution to polarization. I contend that it is not the solution that secessionists think it is.The book is written for a general audience and deliberately eschews unnecessary academic jargon. But it does discuss the patterns in secessionist conflict, it brings the relevant work in political science to bear on the topic, and it even delves into the American constitutional debate on the legality of secession. Along the way, I provide a few dystopian vignettes of how badly and violently I think secession in America would play out.