[1] Rio's inhabitants (called Cariocas, after the Tupi Indian word meaning "white man's home") represent a microcosm of Brazil's ethnic diversity and include people of European, African, and mixed ancestry.

The rich mosaic of areas of the North Zone are socially differentiated by the average level of income of their inhabitants, closely reflected in the urban infrastructure and public services that are locally available.

Both distance from the Centre and elevation serve as determining factors for the location of favelas, since they have been established on all available steep hillsides as well as in undesirable swampy lowlands throughout the Greater Rio de Janeiro area.

Historically, Rio's population grew primarily as a result of domestic migration, which in some years accounted for two-thirds of the city's increase, although many people immigrated from European countries as well.

By that time, almost half of the city's population were Brazilian migrants, most of them born in the states of Rio de Janeiro, Minas Gerais, and Espírito Santo.

Still, the city's population grew steadily and did not begin to taper off until the 1990s, when Rio's limited space, then near saturation, served to restrict further growth.

At the beginning of the 21st century, more than four decades since Rio ceased to be the national capital, a large proportion of federal employees were still based there, along with tens of thousands of state and city workers.