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Administrative division
The administrative division is the oldest nomenclature of territorial units provided for in the law. In accordance with Decree-Law No 46,139/64 of 31 December, administrative regions were distritos (districts), concelhos (councils) and freguesias (communes). Under the terms of the Constitution of the Portuguese Republic of 1976, autarquias locais (local authorities) are collective territorial legal persons with representative bodies, whose purpose is to pursue the interests of the population (Article 235). For the mainland, three categories of local authorities are considered: freguesia (commune), município (municipality, replacing the term council) and região administrativa (administrative region) (Article 236). As long as administrative regions are not actually set up, the Constitution sets forth that the district division must be maintained in areas not covered by the former (Article 291). In autonomous regions, to which the Constitution of the Portuguese Republic grants autonomy, local authorities comprise communes and municipalities. In fact, the Constitution granted the Autonomous Regions of Açores and Madeira a specific form of autonomous organisation, due to their particular geographic, economic, social and cultural characteristics. These regions were granted political and administrative capacity. With the approval in 1976 of the Political and Administrative Statutes of the Autonomous Regions of Açores and Madeira, the island is from then onwards considered to be the first level for those regions in what concerns the administrative division.
The encoding of the administrative regions in the national territory is essential for the use of administrative units in the context of the National Statistical System. This procedure consists in assigning a numerical code - according to a set of criteria for the standardisation of existing encodings, established in 1994 by the Statistical Council (Decision No 86 of 15 December 1994)-to the administrative regions created by the Parliament. Hence, the Administrative Division Code shows a tree-level structure:
  • Level 1: distrito - district in the case of the mainland, and island in the case of the Autonomous Regions of Açores and Madeira, identified through a two-digit numerical code;
  • Level 2: município - municipality, identified through a four-digit numerical code; two of these digits correspond to the municipality within the district;
  • Level 3: freguesia - commune, identified through a six-digit numerical code; two of these digits correspond to of the commune within the municipality.
In each district there is a deliberative assembly, composed of representatives of the municipalities, and a council chaired by the civil governor, who represents the Government and exercises supervisory powers within the district. There are currently 18 districts in mainland Portugal: Aveiro, Beja, Braga, Bragança, Castelo Branco, Coimbra, Évora, Faro, Guarda, Leiria, Lisboa, Portalegre, Porto, Santarém, Setúbal, Viana do Castelo, Vila Real and Viseu.
The municipality’s representative bodies are the municipal assembly (deliberative body) and the local council (executive body). Currently, all municipalities are equal before the law. In 2006 the title of level 2 of the Administrative Division Code was changed from concelho (council) to município (municipality), thereby allowing it to be harmonised with the terminology of the Constitution of the Portuguese Republic (Decision No 219/2006 of the Prime Minister’s Office, published in the Official Gazette, Series II, of 16 February).
The tasks of municipalities and communes are associated with the fulfilment of the needs of local communities, for example as regards socio-economic development, spatial planning, utilities, sewerage collection, culture, environment, inter alia.
In terms of information availability, Statistics Portugal provides a wide range of infra-regional statistical information, namely at the municipality level, in an attempt to meet the growing need for economic and social information at the local level. At the commune level, information is made available stemming from administrative data and censuses that are regularly conducted in Portugal (population, housing and agricultural censuses).

Statistical divisions
In addition to administrative-territorial units, it has become necessary to develop another type of territorial divisions for purely statistical purposes. It is the case of the NUTS regions, defined at the Community level, that make it easier to compare statistical data within the European Union. For the purpose of conducting censuses of population and housing, small statistical territorial units must be delimitated. In turn, the growing concentration of population and economic activity in urban areas and the consequent demand for statistical information resulted in the need to delimitate, for statistical purposes, units that are representative of the urban dimension.
NUTS regions
Census geography
Localities
Portuguese statistical cities
Classification of urban areas
Degree of urbanization (Densely populated, intermediate and thinly populated areas), 2011
 
NUTS regions
The Nomenclature of Territorial Units for Statistics (NUTS) began being used in the middle of the 70’s(*) , in the scope the Economic European Community, between the Eurostat, the European Commission and Member-states, with the goal of allowing a unique, uniform and hierarchical division of territorial units for purposes of statistical production and dissemination.
In the national context, the NUTS was approved in 1986, through the Ministerial Council Resolution 34/86, March 26th, which established three NUTS levels. Based on the legislation, Statistics Portugal created a code system for this nomenclature, aiming its use in the context of National Statistical System (SEN). Although it is desirable to keep some stability, the NUTS has suffered some changes: in particular in 1989, aiming the harmonization with the agrarian regions and areas (decree-law 46/89, February, 15th), in 2002 (decree-law 244/2002, November 5th).
Besides being a contribution to the harmonization of European statistics, the NUTS adoption in Portugal aimed at mitigating the divergences between matrixes of spatial delimitation used in both statistical and dissemination production and, so, allowing for an integrated statistical data analysis.
Until 2002, November 4th, SEN has used a NUTS national code different from the one used by Eurostat regarding all European Union countries. In that year, taking advantage of the NUTS national change determined by the decree-law 244/2002 and by the fact that the European regulation was to be published, the national code was harmonized with the European one. Therefore, from 2002, November 5th, onwards the NUTS code used by SEN is the same as the one defined by Regulation 1059/2003, May 26th, of the European Parliament and of the Council, which annexes were changed by Regulation105/2007, February 1st, of the Commission. It is worthwhile to note European legislation stands above the national one, forcing Member-states to obey the European regulation whenever they define or change their NUTS.
At the top of the NUTS hierarchy, are the European Union Member-states (in the Portuguese case, the first level corresponds to PT - Portugal), and the NUTS code structure has three levels:
  • NUTS I (1 alphanumeric character)
  • NUTS II (2 alphanumeric characters)
  • NUTS III (3 alphanumeric characters)
The fact that in the Portuguese case the NUTS III level is an aggregation of municipalities allows the integration of the NUTS with the Administrative Division Code.
Besides being used as a reference in the data collection, development and harmonization system of regional statistics at European level and in socio-economic regional analysis, the NUTS is also used as a framework for European regional policies. In this respect, the criterion used to elect the regions to be supported by European funds is the NUTS II or III level delimitation. Also, the periodic report prepared by the European Commission every three years on the situation of European regions regarding economic and social development is prepared on the basis of NUTS II level analysis.
Although it is desirable to assure that regions of similar size are coded in the same NUTS level, each of these levels still integrates regions with clearly different sizes in terms of area, population, economic development or administrative power. This heterogeneity reflects, at a larger extent, the existing situation in each of the Member-states.
According to Regulation 1059/2003, "In order to establish the relevant NUTS level in which a given class of administrative units in a Member State is to be classified, the average size of this class of administrative units in the Member State shall lie within the following population thresholds":
LevelMinimumMaximum
NUTS I 3 millions 7 millions
NUTS II 800 000 3 millions
NUTS III 150 000 800 000
If the population of a whole Member State is below the minimum threshold for a given NUTS level, the whole Member State shall be one NUTS territorial unit for this level [Article 3(2)]. However, "If for a given level of NUTS no administrative units of a suitable scale exist in a Member State, in accordance with the criteria referred", in the table above, "this NUTS level shall be constituted by aggregating an appropriate number of existing smaller contiguous administrative units. This aggregation shall take into consideration such relevant criteria as geographical, socio-economic, historical, cultural or environmental circumstances. The resulting aggregated units shall hereinafter be referred to as "non-administrative units". The size of the non-administrative units in a Member State for a given NUTS level shall lie within the population thresholds referred" [Article 3(5)], in the table above.
In the Portuguese case, there are three NUTS I (consisting in the administrative units of Continente, Região Autónoma dos Açores and Região Autónoma da Madeira), seven NUTS II and 25 NUTS III.
The Regulation (UE) no. 868/2014, August 8th of the Commission published in JO L 241 of 13 August established the new territorial limits of reference of the Portuguese NUTS (NUTS 2013). The new version of the Portuguese NUTS applies to the National Statistical System from January 1st, 2015 onwards as a result of the operational agreement with Eurostat. Comparing with the previous version of the Portuguese NUTS, the NUTS level 3 (NUTS III) changes from 30 to 25 territorial units and are now 'administrative units'. The administrative units of reference for Portugal are the "Entidades Intermunicipais", "Região Autónoma dos Açores" and "Região Autónoma da Madeira". The territorial limits NUTS III of Mainland and respective designations are in line with Annex II of Law No. 75/2013 of 12 September, which approved the statutes of intermunicipal entities.
 
Census geography
The preparation and execution of a population and housing census operation require geo-referenced information based on small territorial units. With that goal, Statistics Portugal has developed a system of geographic reference which, containing the administrative delimitation, divides parishes (freguesias) in small statistical areas - statistical sections and subsections. This system is integrated in digital format in the Geographic Information System of Statistical Portugal (BGRI) which is a fundamental structure supporting census processes and, at the same, a tool for census data dissemination.
The statistical section is the territorial unit representing the continuous area of a single parish with approximately 300 dwellings. The statistical subsection is the territorial unit which identifies the smallest homogenous area, whether built-up or not, existing in the statistical section. It represents a block in urban areas, a locality or part of a locality in rural areas or to residual areas which may or may not contain dwellings.
In 2011, the national territory was divided in about 18 thousand statistical sections and approximately 266 thousand statistical subsections.
 
Localities
A locality is a territorial delimitation, defined in the context of census operations, consisting in a population cluster with 10 or more residential dwellings and to which a distinct place name is attached, irrespective of whether it belongs to 1 or more parishes.
In 2011 Census, approximately 26 thousand localities were registered in the national territory.
 
Portuguese statistical cities
Cities show a growing importance as driving forces of economic growth, competitiveness and employment. Law 11/1982, June 2nd, defines the conditions that allow a small town to achieve the city level. However, the legislation does not account for the city territorial delimitation. In this context and based on the legislation that defines cities creation, Statistics Portugal has created the "statistical city" by defining the statistical criteria according which it becomes possible to establish cities’ territorial delimitation.
The statistical city is the territorial unit corresponding to adjustment of the urban perimeter as laid down in the legal instruments concerning land occupation for the settlement with city status, to the statistical subsections perimeter used by Statistics Portugal in the Information Reference Geographical Database (BGRI). This delimitation results from a partnership between Statistics Portugal and municipal councils.
 
Classification of urban areas, 2014
The Classification of urban areas, for statistical purposes, was revised in 2014. The 39th (2014) Deliberation of the Standing Section of Statistical Coordination of the Statistical Council, published in Diário da República (the Portuguese official gazette), 2nd series, No.144, July 29th, 2014, approved the mentioned classification as well as its application to all parishes (freguesias) in the country, replacing the 2009 version.
The new Classification of urban areas (TIPAU 2014) consists, as the 2009 version did, in a triple classification of the national parishes in predominantly urban areas (Áreas predominantemente urbanas, APU), medium urban areas (Áreas mediamente urbanas, AMU) and predominantly rural areas (Áreas predominantemente rurais, APR).
TIPAU 2014, besides allowing for the classification of the national territory in the three categories mentioned above, according to the degree of urbanization, it also provides the definition of "Urban population" as the population residing in predominantly urban areas (APU) (statistical concept 3915) and both the identification and delimitation of urban areas with a specific designation, as sets of contiguous APU parishes confined to municipal boundaries.
TIPAU 2014 is available in two versions: a static one, reported to the Census 2011 dissemination geography (V03485 version), and a floating one, which takes into consideration updates regarding the territorial administrative reorganization of parishes - CAOP 2013 (V03486 version).
This floating version has its starting point in 31/12/2013 and provisionally classifies the changes in the Administrative Division Code that took place following the administrative reform of 2013. The changes occurring after 31/12/2013 are only considered on the 31/12 of each year. In case of data extractions along the year, it is always considered the reference geography on 31/12 of the previous year.
The methodological approach for TIPAU 2014 was based on the 2011 Census statistical section and subsection levels and it followed four steps:
  1. The first step focused on the analysis of morphological criteria on the basis of effective land use through population density (at the statistical section level) and of locality belonging (at the statistical subsection level);
  2. The second step focused on the analysis of the territory by taking into consideration the information of the Municipal Spatial and Land-use Plans (PMOT), which enabled the classification of statistical subsections in two categories: urban soil (statistical concept 3102) and non-urban soil. This information is based on harmonized information available for Continental Portugal in the Map of the Land Use Regime (CRUS) or, directly, on the classes of space and/or urban perimeters of PMOT for the autonomous regions;
  3. The third step was based on the conjugation of results from the application of the morphological criteria (first step) and from the application of the planning criteria (second step), in a single classification of the statistical subsections in three categories:
    • Urban space (statistical concept 7251)
      Statistical subsection that complies with one of the following requirements: 1) classified as "urban soil" according to planning criteria of the Municipal Spatial and Land-use plans (PMOT); 2) it is part of a statistical section with a population density above 500 inhabitants per km2; 3) it belongs to a locality with a population of 5 000 or more inhabitants.
    • Semi-urban space (statistical concept 7250)
      Statistical subsection classified as "non-urban soil" according to planning criteria of the Municipal Spatial and Land-use plans (PMOT) and that has not been previously included in the "urban space" category and complies with one of the following requirements: 1) it is part of a statistical section with a population density above 100 inhabitants per km2 and equal or below 500 inhabitants per km2; 2) it belongs to a locality with a population of 2 000 or more inhabitants and less than 5 000 inhabitants.
    • Predominantly rural space (statistical concept 7249)
      Statistical subsection classified as "non-urban soil" according to planning criteria of the Municipal Spatial and Land-use plans (PMOT) and that complies with all the following requirements: 1) it has not been previously included in the "urban space" or "semi-urban spaces" categories; 2) it has a population density equal or below 100 inhabitants per km2; 3) it does not belong to a locality with a population of 2 000 or more inhabitants.
  4. The fourth step consisted in the transposition of the results for the statistical subsections to the parishes and in the integration of administrative and morphological criteria at the parish level, making it possible to obtain the final classification of these territorial units:
    • Predominantly urban areas (APU) (statistical concept 1070)
      Parish that complies with, at least, one of the following requirements: 1) the greater value of the average between the weight of population in the parish’s total population and of the weight of the area in the parish’s total area corresponding to urban space, with the weight of the area in predominantly rural space not surpassing 50% of the parish’s total area; 2) the parish is the location of the municipal council and has a population of more than 5 000 inhabitants; 3) the parish contains totally or partially a locality with a population of 5 000 or more inhabitants, being the weight of the population in the parish’s total population or in the locality’s total population equal or higher than 50%.
    • Medium urban areas (AMU) (statistical concept 1089)
      Parish that complies with, at least, one of the following requirements: 1) the greater value of the average between the weight of population in the parish’s total population and of the weight of the area in the parish’s total area corresponding to urban space, with the weight of the area in predominantly rural space surpassing 50% of the parish’s total area; 2) the greater value of the average between the weight of population in the parish’s total population and of the weight of the area in the parish’s total area corresponding to urban space, with the weight of the area in predominantly rural space not surpassing 50% of the parish’s total area; 3) the parish is the location of the municipal council and has a population equal or below 5 000 inhabitants; 4) the parish contains totally or partially a locality with a population of 2 000 or more inhabitants and less than 5 000 inhabitants, being the weight of the population in the parish’s total population or in the locality’s total population equal or higher than 50%.
    • Predominantly rural areas (APR) (statistical concept 1084)
      Parish not classified neither as APU nor as AMU.
The methodology followed for the classification of parishes according to TIPAU 2014 follows the one defined for the previous classification TIPAU 2009: the use of objective quantitative and qualitative criteria easily operationalized that ensures comparability between classifications.
The studies that support TIPAU 2014 methodology were developed within the scope of the Standing Section on Territorial Base Statistics of the Statistical Council competence, in a working group involving Statistics Portugal (INE), the Ministry of Agriculture and Sea (MAM), the Directorate-General of Territorial Development (DGT), the Directorate-General of Local Authorities (DGAL), the Financial Institute for Regional Development (IFDR, currently integrated in the Cohesion and Development Agency), the five Regional Coordination and Development Commissions (CCDR), the Regional Statistical Office of Azores (SREA),  the Regional Directorate of Statistics of Madeira (DREM), the National Association of Portuguese Municipalities (ANMP) and the National Association of Parishes (ANAFRE).
 
Degree of urbanization (Densely populated, intermediate and thinly populated areas), 2011
The Degree of Urbanization in 2011 is a classification type of the territory which is based on territorial units LAU 2 (Local Administrative Units level 2 - parishes in Portugal) that allowed dividing the territory of the Member States into three categories (densely populated areas, intermediate areas and thinly populated areas), mainly through criteria of density and population size. This classification is used in some European surveys, particularly in the Labour Force Survey, the Survey on Income and Living Conditions and Tourism Statistics.
The absence of a definition, widely accepted, allowing the delimitation of urban areas, led Eurostat to typify the European Union national territories according to the Degree of Urbanization. The original version of the typology was established in 1991 to indicate the type of area where the respondents to the surveys lived. This typology distinguishes three types of areas: densely, medium and thinly populated. The classification of areas was based on the size and density of population and the contiguity of LAU 2. As the total area of LAU 2 range greatly from country to country, the results showed some bias and limited comparability between countries.
The new Degree of Urbanization (2011) is based on an analysis of the occupation of space by an orthogonal grid of 1x1km referring to 2006. Because the cells have equal size, this new method eliminates the distortions associated with a direct classification based on LAU2.
The revision of the typology Degree of Urbanization is also associated with the revision of the target cities to be monitored by the project Urban Audit 2012/2013. In this context, Eurostat along with Member States sought to ensure harmonization between the densely populated areas and the delimitation of Urban Audit cities that in the Portuguese case correspond to municipalities. This harmonization is relevant for the European Statistical System because it will present results of statistical operations that use the Degree of Urbanization typology for the dissemination of results for all Urban Audit cities of each of the Member States. Thus, it became possible, for example, the provision of the Labour Force Survey results for the Portuguese Urban Audit cities as a whole.
Next, we present the concepts associated with this classification:
  • Densely populated areas: contiguous set of local areas (parishes), in which at least 50% of the population lives in high density clusters. High-density clusters are contiguous grid cells of 1 km2 with a density of at least 1 500 inhabitants per km2 and a minimum population of 50 000 inhabitants.
  • Intermediate areas: contiguous set of local areas (parishes), not belonging to the densely populated areas, each of which has less than 50% of the population living in rural grid cells (grid cells outside urban clusters) and less than 50% of the population living in high-density clusters. Urban clusters are clusters of contiguous grid cells of 1 km2 with a density of at least 300 inhabitants per km2 and a minimum population of 5 000 inhabitants.
  • Thinly populated areas: contiguous set of local areas (parishes), where at least 50% of population lives in rural grid cells.
A local unit (parish) belonging to a thinly populated area or an intermediate area, can be classified as densely populated if it belongs to a group of local units (parishes) with a political function and if the majority of the population of this group of local units (parishes) lives in a high-density cluster. Thus, in the case of Portugal, the typology of degree of urbanization classifies as densely populated all the parishes included in the municipalities corresponding to the cities covered by the European project Urban Audit 2012/2013.
 
Other divisions
In addition to administrative divisions and divisions created for statistical purposes, there are also other territorial units that arise from aggregations of the previous units and that are also used for the dissemination of statistical information.
 
Agrarian and forest regions
In 1989 Decree-Law No 46/89 of 15 February amended the Resolution of the Council of Ministers No 34/86 of 26 March on the adoption of NUTS in Portugal, so as to render compatible the delimitation matrices corresponding to NUTS and the Agrarian classification due to the fact that agrarian regions and areas correspond to a significant share of the national compilation of regional statistical information:
  • NUTS III units then corresponded to the aggregation of agrarian areas or to established agrarian areas;
  • agrarian regions then corresponded to the aggregation of NUTS III units
  • Level 2 units then corresponded to the aggregation of agrarian regions or to established agricultural regions.
The harmonisation of the administrative regions adopted by the Regional Directorates of Agriculture and the Forest Institute that aimed at enabling greater coordination and cooperation among the various regional and sub-regional services of the Ministry of Agriculture and simultaneously to simplify the relationships among these services, farmers and their organisations originated, in 1997, for statistical purposes, the integration of the Forest classification into the Agrarian classification, substantiated in the Agrarian and forest classification. Simultaneously, the breakdown of agrarian regions into agrarian areas was discontinued, given the possibility that there would be as many agrarian areas as municipalities, which ended the previous connection between agrarian areas and NUTS. In view of this, the agrarian area ceased to be statistically relevant and thus only the agrarian and forest region is taken into account.

(*)European Communities (2007), "European Regional and Urban Statistics - Reference Guide", Methodologies and working papers, Luxemburgo