Originally, they were an administrative matter. Since 1856, they make it possible to make a socio-economic profile of a country. The size, composition and living circumstances of the population can be learned about. Reliable data from population and housing censuses have become an indispensable tool for political policy and planning, research purposes, enterprises and private persons. Information from censuses can easily be cross-referenced, to obtain a wide knowledge of whole fields of the economic and social life of civilians.
Censuses are also an excellent tool for the analysis of society developments.
As the series of various data have constantly been kept since 1846, it is possible to examine structural and long-term changes. On 1 March 1991 a classic population and housing census on the basis of the National Register was held. The procedure was as follows. The census forms were collected by the municipal officials, then each municipal administration deposited them at or sent them to the regional center of Statistics Belgium the administration depended from. After receipt and control of the documents the regional centers started with the registration of the forms by optical reading.