Municipal open data portals have been criticized for their inability to fulfill the promises of transparency, citizen participation and economic development that are supposed to accompany data release. Based on an analysis of certain aspects of the City of Montréal’s open data portal and interviews with reusers of these data, we show that the limitations observed stem – at least in part – from an absence of consideration of the municipality’s political and territorial reality. Three facts contribute to this absence: 1) the Montreal open data portal was designed as a public service; 2) it was created upstream, and not based on the identification of possible needs of the population or the territory; and 3) the relevance of the published datasets raises questions with respect to the promises made. These elements invite us to better link open data portals to objectives and needs that are first and foremost local, while inserting them into a broader framework for achieving the initial democratic and economic promises.