Rio de Janeiro
Rio has more people living in slums than any other city in Brazil, according to the 2010 Census. More than 1,500,000 people live in its 763 favelas, 22% of Rio's total population. São Paulo, the largest city in Brazil, has more favelas (1,020) in sheer numbers, but proportionally has fewer people living in favelas than Rio.
History of Rio de Janeiro
In the mid-20th century, metropolitan Rio de Janeiro grew beyond its formerly narrow confines because of migration from other parts of Brazil, as well as a high rate of natural increase. The suburban population more than tripled to some 1.5 million between 1940 and 1960, at a time when the city proper exceeded 3.3 million. Following the transfer of the national capital to Brasília in 1960, Rio's rate of population growth slowed somewhat, although the suburban population continued to mushroom. By 1980 there were more than 5 million residents in the city and 3.6 million in the suburbs. Although subsequent growth continued at a lesser rate, by the early 21st century the metropolitan population exceeded 11 million, of which nearly half resided in the suburbs.