With the largest extent of tropical forest in the world, the dynamics of forest loss and fragmentation in Brazil have been the focus of attention for over 50 years. Global shifts in trade to the Pacific and growing infrastructure, however, threaten the western end of the forests in the Andean region, including the Amazon. Research combining spatial and socioeconomic analyses, as well as exploring the 20th-century history of the region, reveals three surprising findings. First, wedges of deforestation are strongly associated with directed colonization projects more than 40 years old. Second, although pastures are the end state of much formerly forested land, demand for beef is a poor predictor of this process and urbanization following infrastructure upgrade is a better correlate. Finally, coca cultivation, widely believed to be a motor of forest loss, contributes little to the process both directly and indirectly. Instead, the clearing of these forests corresponds to the transformation of nominally state-owned forests into private properties, and occurs in tandem with local urbanization and despite overall rural depopulation.