RIO DE JANEIRO The 2016 Olympics began with a promise. When the International Olympic Committee chose Rio de Janeiro as the host in 2009, local officials said billions of dollars of investment would be poured into these first games held in South America, transforming Rio into a vastly better city.

The favelas the unofficial, often impoverished communities that line Rios iconic hills would benefit too, they said. The government would finally deliver some of the basic services that the favelas had long lacked, improving roads and housing, sewage, sanitation, health care and education.

By the time the games opened in August, though, those promises had proved hollow. Rio did invest billions in transportation and infrastructure, but most of it focused on the already wealthy areas of town.

They spent 39 billion reals on the Olympics, said Michel Silva, a community journalist in Rocinha, the largest of the citys favelas. (Thats roughly $12 billion.) And the favelas got nothing.

They werent just excluded. At times, the favelas were targeted by bulldozers making way for Olympic venues and by police who promised to make Rio safer for everyone, it seemed, except the favelas. The public services they were promised never came, and existing services, like the bus lines that once connected some favelas to the rest of the city, were altered or cut altogether.

But something else happened in the favelas, home to nearly a quarter of Rios 6.3 million residents, in the years leading up to the Olympic Games. People in the neighborhoods came together in anger, frustration and hope to fight for their way of life. The Rio Olympics and the ills they brought helped the favelas find their political voice.

People in the favelas now more than ever have an identity and understand their value, said Theresa Williamson, executive director of Catalytic Communities, a neighborhood development organization in Rio.

They didnt know they could fight for this, she said.