Do informal settlements contribute to sprawl in Sub-Saharan African cities?

•Analyzes sprawl via street network connectivity for seven secondary cities in Tanzania.•Contrasts connectivity of informal and planned urban areas based on remote-sensing data.•Uncovers 12.8 % lower network connectivity in informal settlements in a pooled regression.•Shows substantial heterogeneity in informality's association with sprawl for different city types.•Between-city heterogeneity points away from attributing informality to sprawl per se in secondary cities in Sub-Saharan Africa. Cities in Sub-Saharan Africa are recognized as drivers of development but also as internally disconnected and sprawling. Informal or “unplanned” settlements are often suggested to hamper sustainable growth, while commonly being labeled “sprawl” by default. This notion is addressed in the present paper, which aims to analyze empirically whether informal settlements do contribute more to sprawl than planned areas, in the setting of Sub-Saharan African cities. To this end, the street network accessibility of buildings in informal and planned areas is compared, to understand compactness beyond population density under overcrowding. The setting consists of Tanzanian secondary cities. To trace the effect of informality on compactness within and across cities, regression analysis is used, while controlling for other characteristics of urban structure such as population density. Pooled regression results indicate an approximately 12.8 % lower connectivity for informal settlements. Importantly, this association is not homogeneous and varies substantially across different types of cities. In several cities, informality's impact on connectivity is relatively pronounced, pointing to sprawl. In other cities, no significant relation between informality and connectivity is found. This observable ambiguity underlines the unclear relationship between informality and sprawl. This may be considered within the policy discourse on urban sprawl in Sub-Saharan-Africa.