Approximately 30 per cent of the world's tropical forests are found in Brazil. In a continuing effort to decentralize the Brazilian population and exploit undeveloped regions, the Brazilian government constructed the Cuiaba-Port Velho highway through the province of Rondônia. Completed in 1960, the road serves as the access route for infrastructural development in the region, previously occupied solely by indigenous people. In 1975, the region was still relatively pristine, with much of the forest intact. By 1986, the distinctive fishbone pattern of forest exploitation had appeared and then expanded dramatically. The highway has become a major transportation route for immigrant farmers seeking income-producing opportunities. Migration into the area continues unabated.