‘Crossing the line’: A boundary transgression model of resistance to desegregation

Informal patterns of spatial division often persist in historically divided societies where segregation has been officially dismantled. This paper presents a theoretical model to explain why, focusing on the desegregation–resegregation dynamic. The Boundary Transgression Model highlights two interconnected pathways - social psychological and human geographic - that shape intergroup relations under conditions of change, fostering the re-emergence of distance, division, and contact avoidance. It frames resistance to desegregation as a response to constructions of boundary transgression, “ruptures” to the socio-spatial order. The argument is developed through a 25-year research programme in post-apartheid South Africa and post-accord Northern Ireland. The paper also proposes an expanded integration strategy, complementing the prejudice reduction model of change in social psychology. This aims to transform not only person–person but also person–place relations, bringing social psychologists into dialogue with environmental psychology, geography, and urban sociology, and with practitioners in urban design, public policy, and architecture.