[citation needed] The blackout involved São Paulo, Rio de Janeiro, Minas Gerais, Goiás, Mato Grosso, Mato Grosso do Sul and Rio Grande do Sul, affecting an estimated 75 to 97 million people.
Brazil was undergoing a severe investment crisis during 1999, which limited spending on maintenance and expansion of the power grid.
This caused the system to break in many pieces, São Paulo and Rio de Janeiro states were split with a few areas remaining online.
Most of the Minas Gerais system remained online, and powered Brazil's capital, Brasília, as well as the state of Goias and some of Espirito Santo.
[4] In São Paulo, traffic authorities announced they closed the city's tunnels to prevent robberies.