As imprisonment became the usual sanction for many offences, what has been called the “carceral archipelago” developed in the course of the 19th century. The common goal of Montreal constitutes a good example of the penal logic put into place in the 19th century. A summary global analysis of its population (including offences, length of incarceration, age and ethnic group) makes it possible to better see how this logic operated and to locate it chronologically in terms of continuity and break up. Despite major changes throughout time in offences and types of population, the prison remains steadily characterized by continuity, as it introduces the immobility of a repressive space open to various ideologies.