The Gauteng City-Region (GCR) in South Africa is a paradigmatic example of extended urbanization, in which the legacy of mining and apartheid continue to impact spatial practices and the experience of everyday life. The dynamics between urban centralities such as Johannesburg and regional-scale peripheries established by this legacy characterize the "spatiality of poverty" that exists in the GCR today. Yet the relational urbanization processes occurring on these under-researched urban peripheries are also driven by the choices and strategies of people, or "popular agency," as they negotiate both local and regional-scale spaces in pursuit of opportunities. Utilizing the northern part of the GCR as a case study, the article presents ethnographic research including a purposive sampling of informal settlement residents, government officials, and planning experts to discuss how socio-technical strategies focused on capital expenditure for infrastructure and affordable housing often reinforce existing socio-spatial inequalities. At the same time, new "popular centralities" are emerging as individual people exercise their agency to move around the region and produce alternative forms of space. Considering the agency of people calls for a decentered and transdisciplinary approach to urban analysis and spatial planning, with significant implications for both the theory and practice of urban and regional studies today.

Despite the ‘mobility turn’ in urban studies, there is surprisingly little research into the role people’s everyday movements play in driving urbanisation processes. As this paper discusses, one reason this has not occurred is because understanding this relationship requires both quantitative and qualitative knowledge, including geospatial locations and patterns as well as why people choose to move the way they do. Few studies employ mixed methods to this end; instead, many quantitative approaches focus on the use of big data and many qualitative approaches remain focused on sites themselves rather than the movements between them. This methodological gap can preclude operationalising findings and proves particularly detrimental when research is conducted into areas with high levels of poverty and inequality. In response, this paper presents a mixed-methods approach to studying urbanisation, using volunteered geographic information (VGI) to map regional-scale movements in the Gauteng City-Region (GCR). Exploiting the potential of smartphone technology, this methodology operates at the interstice of quantitative and qualitative research, describing both macro-scale mobility patterns and the micro-scale decisions behind them. Using the case study of the GCR, it highlights movement as a strategy for those living in poverty, who can utilise the entire region as a resource to subvert entrenched inequality. ‘Thinking through people’ suggests that a new ontology of categories describing urbanisation processes in terms of movement could connect empirical research into poverty and inequality to theory, and be used to create an epistemology of the urban from below. Thus, this paper contributes to advances in urban studies methods as well as to debates on urbanisation, relational poverty and socio-spatial inequality.

This article interrogates the term “periphery” by examining the forms of urbanisation unfolding in the Gauteng City‐Region (GCR) of South Africa. Among the urbanisation processes identified, it focuses on two, situating them among debates on informality and defining new vocabularies of urbanisation. Aligned with discussions of peripherality as a social phenomenon, the article first depicts how some marginalised groups of people using transversal means carve out “toeholds” near urban centralities and opportunities. Second, it conveys how peripherality is also a geographical phenomenon, describing “aspirational” mass housing for the lower‐middle class on urban peripheries that can generate unexpected forms of precarity. The article concludes that toehold urbanisation and aspirational urbanisation drive peripheralisation in the GCR, and considers the implications of these concepts for critical geography and urban studies.