This city went from being an undesirable place to live in to a more sustainable place. Before, poverty was consuming people’s interest for survival. Overpopulation did not help to improve the living conditions in the site. According to the PreDesign Word Press, it “increased by about 900 people each week for a period of 40 years,” and the economy did not improve as the population grew.
The need to redesign the systems thinking (in other words and in this case, the way the government was taking care of their people) of Curitiba was crucial because the quality of the site was declining rapidly. Then in 1965 a Master Plan was proposed by the architect and urban planner, an current major of the place, Jaime Lerner. As many of the past blogs have mention, design plays a role in every field, in this case architecture and the redesigning of Curitiba.
Lerner decided that there was a need of rethink the way society was living in Curitiba. The main goal was to improve the quality of life at the site; therefore the goal was to “provide economic support for urban development.” The systems thinking that Lerner applied was to educate the people about recycling, reusing, and reduce. He changed systems thinking in the site and the people's way of viewing their hometown. They no longer saw their government as an institution that only wanted to take advantage of their people, now they worked along with them.
He re-designed the transportation system, as mentioned past blogs; he created a massive transportation system that involved the reusing of existing buses, instead of building a new underground transport system. But, not only did he improve the transport system, but the quality of living at the site, because he improved the cultural value the community had for their city.

Furthermore, Lerner changed the ethics of the society by providing a better quality of education and by teaching the community to be more sustainable and self-sufficient. He additionally redesign the society's interaction towards its own community; thus, he created more of a sense of community in the city.
Lerner not only redesigned the aesthetics of the site, and the ethics of the place, but his new approach to design transformed the entire place from being an unsustainable place to live, where overpopulation and poverty were the main issues, to being a sustainable model for the entire world.
References:
http://www.dismantle.org/curitiba.htm
http://predesign.wordpress.com/2007/04/17/sustainable-history-of-curitiba-brazil-13/
http://www.nytimes.com/2007/05/20/magazine/20Curitiba-t.html
Photos:
http://farm3.static.flickr.com/2131/2361012405_c87976293d.jpg
http://www.escapeartist.com/efam/69/parkwater.gif