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.
Americas
The Americas are home to over a billion inhabitants, two-thirds of which reside in the United States, Brazil, or Mexico. It is home to eight megacities (metropolitan areas with ten million inhabitants or more): New York City (23.9 million), Mexico City (21.2 million), São Paulo (21.2 million), Los Angeles (18.8 million), Buenos Aires (13.8 million), Rio de Janeiro (13.0 million), Bogotá (10.4 million), and Lima (10.1 million).