Borders are ubiquitous in political life. Indeed, borders are perhaps even constitutive of political life. Borders are inherent to logics of inside and outside, practices of inclusion and exclusion, and questions about identity and difference. Of course, there are many different types of borders that can be identified: divisions along ethnic, national or racial lines; class-based forms of stratification; regional and geographical differences; religious, cultural, and generational boundaries; and so on. None of these borders is in any sense given but (re)produced through modes of affirmation and contestation and is, above all, lived. In other words borders are not natural, neutral nor static but historically contingent, politically charged, dynamic phenomena that first and foremost involve people and their everyday lives.

Ostensibly, this book focuses upon one particular type of border: the concept of the border of the state. I say ‘ostensibly’ because, as I hope will become obvious, different types of borders inevitably fold into one another: the notion of maintaining sharp, contiguous distinctions between anything is impossible and inevitably breaks down. In a common understanding of the term, the concept of the border of the state refers to ‘external’, ‘interstate’ or ‘international’ borders that delimit and delineate states as independent entities in the state system. According to what John Agnew has referred to as the ‘modern geopolitical imaginary’, state borders are taken to be territorial markers of the limits of sovereign political authority and jurisdiction, and located at the geographical outer edge of the polity.