Alger is a former French department in Algeria. The département of Alger existed between 1848 and 1962.
Considered as a French province, Algeria was departmentalised on 9 December 1848, thereby operating according to the same administrative structure as metropolitan France. Three civil zones (départements) replaced the three beyliks into which the Ottoman former rulers had divided the territory. The principal town of the central département, also called Alger, became the prefecture of the eponymous département. The two other Algerian departments were Oran in the west and Constantine in the east.
The département of Alger covered an area of 54,861 km², and comprised six sub-prefectures: these were Aumale, Blida, Médéa, Miliana, Orléansville and Tizi-Ouzou.
It was not until the 1950s that the Sahara was annexed into departmentalised Algeria, which explains why the département of Alger was limited to what is the north-central part of Algeria today. Until 10 January 1957, when the Sahara regions received their own administrative structure, these territories were administered by the département of Alger.
The 1954 census recorded the stated religious affiliations of the population. The majority in the département of Alger declared themselves to be Moslems. In the city of Alger itself, however, 296,041 or 46% of the 645,479 people counted were declared to be non-Moslems. This placed Alger second only to the city of Oran in terms of the proportion of the population stating that they were non-Moslems. Non-Moslem appears to have been seen as a surrogate description for people of European origin.