This PhD thesis deals with the conditions of illegal border crossing of the African migrants in the south of Spain and with their logics of insertion in the Andalusian province of Almeria and beyond, in the European space. By questioning the power struggle between migrants and State, this thesis insists on the migrants’ capacity to move and it highlights the ambivalence of governmental institutions, partly linked with the economical function of undocumented migrants. The analysis of connections between the strategies of undocumented migrants and the logics of institutions and local actors are based on the description of the interactions, transactions and existing conflicts between the migrants recently arrived, those who are already installed, the NGOs, the managers, the police forces, etc. The ethnographic study of the migrants’ experience before and after crossing the border reveals the importance of social networks to reach Europe and to look for housing, employment and papers. At the same time, it points out the function of Spanish associations for the most vulnerable migrants. On one hand, the governmental institutions fluctuate between control and tolerance; one the other hand, the migrants glide between constraints and strategies, regularity and irregularity. Their migration, built on several stages, constitutes then a real “snakes and ladders”. Almeria represents a stage where it is possible to look for papers. This province, specialized in agriculture, has an informal “uncovered” economy: everybody knows it including the authorities. Almeria centralizes the African migrants who are in a precarious situation, whatever the time of their arrival in Europe. This thesis proposes to qualify the mobility of those undocumented migrants as “a mastered roving”, mastering that is essentially done through social relations and the constitution of social networks. The attention turned to the construction’s terms of the migratory project after the border crossing also allows generating the notion of “zero square”. This means a special space-time, intermediate between the border crossing and the insertion in the European space; a time more or less lengthy, characterized by the repetition of basic survival situations that authorize the maximal exploitation of the migrant, who, therefore is looking for the means to avoid this repetition or to get out of it.
