Metropolitan region is the set of different municipalities close and interconnected with each other, usually built around a metropolis, a central and more developed city.
Metropolitan regions are formed through the phenomenon of conurbation, when nearby cities grow until they merge with one another, giving the impression of constant continuity. Typically, the municipalities that are close to the host municipality are called satellite cities.
know more about Conurbation.
For example, Rio de Janeiro is the host city of the Metropolitan Region of Rio de Janeiro, which is formed by other municipalities (satellite cities), such as: Duque de Caxias, Niterói, Magé, Nilópolis, Nova Iguaçu, São Gonçalo, among others.
There's a lot advantages and disadvantages in living in metropolitan areas, the main qualities being the availability of a wide range of public and private services transport services to different areas of the region, the large labor market and the great infrastructure of services, whether paid or free.
On the other hand, pollution, the high cost of living, traffic jams (due to the large number of vehicles) and the high crime rate are some of the main disadvantages of the regions metropolitan areas.
Brazilian metropolitan region
In Brazil, the Federal Constitution of 1988 determines that the state governments are responsible for stipulating the metropolitan regions of their respective states, through laws. In this way, governments gain autonomy to plan and implement the best infrastructure projects and the integration of collective public interests.
For a given area to be declared a metropolitan region, certain specifications must be met, such as the number of inhabitants of the central city (megalopolis), which must be equal to or greater than 800 thousand.
But, depending on the characteristics of the region, an area can be declared metropolitan even with a population of less than 800 thousand inhabitants in the central city. In this case, the so-called emerging metropolitan regions need to have a demographic density equal to or greater than 60 inhabitants per km2, having more than 65% of the population economically active and working in urban activities, among other conditions.
Currently, there are 70 metropolitan regions in Brazil, divided between the main urban centers of the country, with the states of Paraíba, Paraná and Santa Catarina having the largest number of metropolitan regions in the parents.
See also: meaning of Metropolis.