This study assesses the extent to which public high schools become more or less socially mixed after families are allowed to choose schools outside their designated catchment areas in a mid-sized Canadian city. We draw on settler-colonial theory, critical human geography, and critical social theory while applying a critical mapping of school choice. We find that the city's high schools are racially and socially segregated, with the most affluent families with European backgrounds concentrated on its west side, and the low-income families with Indigenous and racialised backgrounds clustered on its east side. The west side also has specialised choice programmes that facilitate the social reproduction of both the local residents and mobile students from the rest of the city who choose the programmes and are from advantaged backgrounds. Based on these findings, we argue that school choice practices reinforce school (re)segregation.