Analyzing open data policies, this thesis investigates the effect of the circulation of data on urban government. This political sociology of data, which analyses jointly the transformation of data and actors associated to them, highlights the pluralism of the politics of urban data. Based on an ethnographic investigation inside the Metropolis of Lyon, the thesis studies the open data policy in the making. In addition, 70 interviews, archive material and a partial comparison with North-American cities were used for the analyze. Following the chain of open data, the thesis emphasizes a tension between attachment and detachment. Attached to vast socio-technical networks, data must be detached from their initial environment to circulate, befor...