The amazing thing about Curitiba is that it wasn't DESIGNED to be a green city. It used to have horrific problems with the shanty-towns outside the city proper, built from cardboard, corrugated sheet metal, and anything else the people could find to provide at least some shelter from the elements. Trash filled the "streets", and the fire trucks couldn't fit between the shanties. So when they caught fire, the whole thing would just burn. The mayor of the city had a brilliant idea to exchange bus tokens for bags of trash that had been sorted for recycling. Within a matter of months, the trash was gone, and the people who lived in the shanty town could ride the bus into the city to get jobs. Within a matter of years, it was named a UNESCO World City. They just saw how one tiny change could have a huge impact, and kept making more and more tiny changes...