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
When Rio de Janeiro, which had formerly been the capital of the Empire of Brazil, became capital of the First Brazilian Republic in 1889, it was already a considerable community. At the time of the 1890 census, it had more than 520,000 inhabitants on 61 square miles (158 square km), ranking it as the largest city in Brazil and one of the larger cities in the world. The 1891 constitution designated it the Federal District.