The urban network presented in this item is the result of a study made by IBGE (Instituto Brasileiro de Geografia e Estatística – Brazilian Institute of Geography and Statistics), for the whole national territory*. In this study a classification of urban centers was primarily established, and afterwards, a delimitation of its areas of operation, giving priority to the territorial management function.
For the identification and hierarchization of the nuclei of territorial management were primarily assessed levels of administrative, legal and economic centrality, besides complementary studies, focusing on different equipment and services – activities of trade and services, financial activity, higher education, health services, internet, open television broadcasting networks, and air transport. In a second stage the links between cities were investigated in order to establish the areas of influence of the centers, and also to establish the articulation of the networks in the territory. And finally, urban centers were hierarchized taking into consideration the classification of the territorial management centers, intensity of relationships and extent of the region of influence of each center.
The Brazilian cities were classified in five big levels and these were subdivided in two or three sublevels:
1. Metropolises – urban centers that are characterized by their large size and strong relationships with each other, besides generally possessing an extensive area of direct influence. There are three sublevels: Big national metropolis, National metropolis and Metropolis.
2. Regional capitals – centers related to the top layer of the urban network. They have managing capacity in the level immediately below of those of the metropolises, and an area of influence in regional scope, being referred as destination for various activities by a large number of municipalities. There are three subdivisions: Regional capital A, Regional capital B and Regional capital C.
3. Sub-regional centers – centers with less complex management activities; they have a more reduced area of operation, and their relationship with centers that are external to their own network occurs mainly national Metropolises. They are subdivided in two groups: Sub-regional center A and Sub-regional center B.
4. Zone centers – smaller centers with influence on a restricted area; exercise basic management functions. They are subdivided in Zone center A and Zone center B.
5. Local centers – cities whose centrality and performance do not go beyond the limits of the municipality, serving only its inhabitants, predominantly their population is of less than 10 thousand inhabitants.
In Rio Grande do Sul the capital represents the highest level in this classification. The urban network of Porto Alegre comprises the states of Rio Grande do Sul and Santa Catarina, dividing the area of Florianópolis with Curitiba. The network is formed by Regional capital A Florianópolis; Regional capitals B Caxias do Sul, Passo Fundo and Santa Maria; Regional capitals C Ijuí, Novo Hamburgo-São Leopoldo, Pelotas-Rio Grande and Criciúma; Sub-regional centers A Bento Gonçalves, Erechim, Santo Ângelo, Bagé, Lajeado, Santa Cruz do Sul, Santa Rosa, Uruguaiana, Rio do Sul, Caçador, Itajaí, Joaçaba, Lages and Tubarão; and Sub-regional centers B Carazinho, Frederico Westphalen, Cruz Alta, Balneário Camboriú, Brusque, Concórdia, São Miguel do Oeste, Xanxerê, Araranguá, Videira and Balneário Camboriú.
* IBGE – Regiões de Influência das Cidades (Regions of Influence of Cities) – REGIC 2007