This article develops the concept of "urban frontier" to explore conflicts over state regularisation of city edge informal settlements in Zimbabwe's capital Harare. It conceptualises the presence of "lawless" urban frontiers and "illegal" territorial authorities in capital cities as expressions of a permissive form of central statecraft. In so doing, the article takes forward debates over the politics shaping the margins of Africa's rapidly expanding cities, redressing scholars' tendency to neglect central party-state strategic calculations and party politics in their analyses of unregulated settlements. Dominant interpretations generally hinge on state absence or weakness and emphasise localised influences. The case of Harare's highly politicised city-edge informal settlements reveals the inadequacy of apolitical approaches particularly clearly, as all were controlled by the ruling ZANUPF party. The conflicts provoked by regularisation provide a lens on disputes within the ruling party, which we interpret as disputes over different forms of clientalist statecraft. Analyses of urban frontiers can thus help move away from generic one-sizefits-all explanations of informality and patronage politics in Africa's expanding cities.