Faced with the rapid growth of African cities, states fail to produce enough housing for the entire population and the most vulnerable families go living in the outskirts of cities, in areas so-called "spontaneous settlements". Built out of the formal and legal process of urbanization, these areas are often invisible in the planning documents, although they may harbor the majority of the urban population. In Burkina Faso, these districts are called “non-lotis”. Despite their informality and their invisibility, these neighborhoods “in between” – social, spatial and legal “in between” - are an integral part of the city’s urbanization process and materialize a new type of urbanity, halfway between rural and urban and between "formal" and "informal".