population Censuses are a way of exhaustively counting the population of a country,
provide social and demographic characteristics of persons (age, marital status,
studies, etc.) and are the top ranking operation within official statistics activity.
The first modern Census dates back to 1768 and from 1950 onwards they were called
Population and Housing Censuses, as they linked the characteristics of the inhabitants
with the dwellings in which they lived. The first demographic Censuses of the
21st century were carried out with a reference date of 1st November 2001 and are
the latest data available.
Differences between the Census
and the Register
The Population Census is carried out every 10 years using
exhaustive questionnaires that are sent to the population. The figures are of
a merely statistical nature, in other words, they are not official population
figures and they are protected by statistical secrecy. By using the Census data,
the social and demographic characteristics of the population can be understood
The Municipal Register is an administrative register and each
city council is responsible for putting it together and maintaining it. Its purpose
is to prove which persons regularly reside in a municipality. Its content is stipulated
by law and the data collected for its development come from administrative files.
The result of this data are the population figures, which are declared official
by Royal Decree. The reference period for the data is the 1st January of each
are developed with the aim of understanding the future population, distributed
by sex and age. Three demographic phenomena are taken into account for their calculation:
mortality, birth and migration. In order to develop these projections, hypotheses
on the long-term development of these phenomena are drawn up, using the latest
Population Census as a base.
Due to the strong uncertainty over the development
of numbers of foreigners entering Spain from 2000 onwards, it has been decided
that projections undertaken using the 2001 Census population data be developed
using a different hypothesis on future immigration, taking into account two different
The projected populations
are susceptible to revision, in terms of any errors in the predictions for all
or some of the components. In any case, there will be a revision when figures
are available for a new Census or population count.