Paris’s Gare du Nord is a heterogeneous site of intersecting trajectories, conflicting representations, and myriad practices. By comparing its 1864 construction with its current form, I argue that the shift from exclusionary spatial control measures to an open access model based on ideals of transparency engendered new practices of control and policing. I then turn to the effects and tensions of this new open exchange model, examining the concrete social exchanges during which policed station users – mostly black youth from the peripheral suburbs-perform desire and authority, staking their claim on the public space of the capital. This ethnography sheds light on how these exchanges are fundamental to the ways in which new boundaries are produced and performed during the epoch of so-called democratization of Parisian public space.