Borders are an invention, and not even an especially old one. Predated by the printing press by a good 200 years, borders are constantly under revision. Even the zone of a border itself, the Supreme Court has held, extends far beyond the technical outline of a nation. Imagine a border as the human-made thing that it is, and it’s no longer surprising that it takes a multitude of forms: a line on a map, a fence, a bundle of legal agreements, a set of sensors, a room in an airport, a metaphor.
As Elia Zureik and Mark B. Salter explain in a book on policing, a controlled border creates the notion that domestic space is safe. Protecting “the border” safeguards the home, the family, and a way of life. This idea of safety is so potent that it has shut down the United States government.
But the border itself—the line on a map, or the gate at a crossing—isn’t what’s at issue; it’s the idea of the border, a membrane that defines a nation while maximizing its market power.
A wall does not make a border, or at least it hasn’t in Europe since roughly 1648, when the Treaty of Westphalia was negotiated. In previous eras of human civilization, walls were used to define territory, in part because there was not a complex legal regime hammered out over time to rely on. “Rather than being used as political boundaries, such constructions, including the Great Wall built in the Qin Empire, served more as defensive barriers, a basis for further expansion, and a platform for the control and regulation of the flow of goods and people,” writes the political scientist Manlio Graziano in What Is a Border? “The state borders with which we are familiar today have very different characteristics: They are measured, drawn on a map, marked on the ground, and have a legal significance generally recognized by all parties involved.”