Johannesburg and the broader Gauteng City-Region in which it is located are considered to be the economic powerhouse of South Africa. This has led to massive population growth in the region, as well as severe inequality. Given South Africa’s history of racially excluding black South Africans from urban areas, ongoing research in this area has to analyse land cover and define ‘sprawl’ in a context where the technical language has politically loaded overtones. This article tries to understand the scale of informality within a broader examination of urbanization and sprawl. It concludes that in the absence of a formally adopted urban edge and under massive pressure from population growth (natural and via migration), formal dwellings (residential and economic) have grown unchecked, and informality is now growing at high speed and also largely without regulation or control. With no apparent political will to stop urban sprawl, both informal and formal covers are steadily pushing towards provincial borders, while densifying in Johannesburg in particular.