The security state is expanding through digital border control and migration management. Based on twenty-eight months of ethnographic fieldwork in northern and central Mexico, I examine how the Mexico-US border becomes displaced across territorial and digital boundaries into various domains of social life along the migrant trail. Previous studies emphasize the political dimensions of surveillance within security states. By studying encounters between asylum-seeking migrants, humanitarian workers, US officials and software engineers acting under punitive asylum policies and digital innovation, my research interrogates how the sociotechnical development and implementation of CBP One™, a border-crossing smartphone app, generates bureaucratic, expressive and popular cultural forms that enforce and resist the transnational im/material bordering and surveillance practices of digital security states in the twenty-first century.