The Southern Interoceanic Highway, also called Interoceánica Sur or “IIRSA Sur (Peru-Brasil)”, is a recently completed road connection between the Peruvian coast and Brazil. Inaugurated in 2011 (with a car race), it forms the southern axis of three transatlantic corridors within a development plan of the Initiative for the Integration of the Regional Infrastructure of South America (IIRSA). As the only highway connection between Brazil and Peru it was supposed to stimulate trade and tourism, but now rather seems to trigger further road construction, illegal mining and deforestation in the Peruvian Amazon basin, particularly in the formerly isolated Madre de Dios region.
The Interoceánica came with the promise to boost the economic integration of the Brazil-Peru border region and trade between the two countries. Proponents noted that this would facilitate Brazilian exports to the Asian market due to terrestrial access to Peruvian ports and, as it was proclaimed, also benefit Peru by promoting tourism and connecting some of its isolated agricultural valleys with the west of the country and becoming the link between the world’s biggest emerging economies, China and Brazil. It was even celebrated by the Peruvian president as man’s triumph over nature and distance. As it turned out in 2018, a number of high-level officials in Peru, including the then-president Kuczynski, were involved in the Brazilian Odebrecht corruption scandal, which included several construction bids of the Interoceánica, making it some critics call “the most corrupt highway in the world” . Of particular relevance was certainly the highway section 3 which descends from the Andes to Puerto Maldonado and from there further to the Brazilian border. Here, numerous segments have been newly constructed or renovated and journey time was drastically reduced, which clearly benefited local residents. For example, the trip between Cuzco and Puerto Maldonado takes now about 10 hours of driving whereas before it could have taken several days to weeks during the rainy season. To the west, the highway splits up to reach the Peruvian coastal cities, while to the east it connects to Rio Branco in the Brazilian State of Acre to then continue via the already existing BR-364 and the State of Rondônia to the Atlantic coast. Thus, besides just better connecting the two countries and Brazil with its trading partner number one China (so at least the idea), the new corridor has significantly increased the regional and economic integration of the border region between Acre and the Ucayali and Madre de Dios departments in Peru, an area that has been recently confronted with a series of socio-ecological conflicts. 
To come straight to the point, the main impact of the Interoceánica construction does not result from the road’s pavement or the building of bridges but the numerous indirect consequences of the highway in integrating a formerly isolated region and incentivizing settlements and side roads along the way, thereby advancing environmental and social damage. This does not come as a surprise as experts have warned about these impacts long before the infrastructure offensive. A number of civil society organizations, e.g. the Upper Amazon Conservancy, ProPurús, FENAMAD, or ACCA, have voiced criticism as the highway has triggered economic activities along the way and the construction of a number of secondary roads in the Amazon basin, bringing indigenous territories closer to the deforestation frontier and facilitating access for gold miners and loggers. Southworth et al. (2011) note the crucial role of road construction and infrastructure improvements in driving land cover and land use change which is exemplified by the correspondence between deforestation and road paving in the border region of Acre, Madre de Dios and the Bolivian Pando, particularly along the Interoceánica. A main consequence of better infrastructure in the region has been migration, particularly of poor people who seek to make a living from informal gold mining. Jensen et al. (2018) note that the Madre de Dios region has faced such immigration for decades but the opening of the Interoceánica, in combination with the proliferation of illegal mining, has intensified this trend. Along the highway section that descents from Cuzco numerous gold rush settlements have popped up, usually cutting dozens of new roads into the forests and polluting the rivers with mercury. A Caritas representative from Puerto Maldonado reports that more than 200 people per day would migrate from the Andes into the region, resulting in an estimated number of 30,000 people who seek to make a living from illegal gold mining. Some municipalities have already alerted against the worsening environmental situation but government institutions seem to weak to intervene. A recent study on the so far economic impact of the highway has come to the conclusion that commerce between Peru and Brazil was not notably stimulated and the share of goods transported by highway remained insignificant (among others because the road is too steep for Brazilian soy transports and it is still cheaper to ship container directly from Sao Paulo). Instead, also this study confirms that unregulated gold mining in the Madre de Dios region has benefited most from the paved road and expanded during the last years (which does not necessarily mean that miners themselves have profited as they usually work under precarious, hard conditions). The advancing road construction in the Amazon has moreover produced a number of socio-cultural problems for nearby communities, for example through an increase of crime and invasions of loggers and miners in indigenous territories. A local governor in Madre de Dios notes that Interoceánica has so far brought more problems than progress; it has increased crime, drug-addiction, deforestation, uncontrolled migration and ecological destruction in the region. The city of Puerto Maldonado has moreover experienced a rapid increase of housing and land prices which induced people to further migrate to nearby rural areas and forests. Similarly, Brazil’s FUNAI reported in 2012 that in two communities affected by the Interoceánica construction an increase in logging, illegal hunting and fishing was noticed and that the influx of construction workers and miners in the region has increased alcoholism, prostitution, and harassment of the indigenous population.  
The Monitoring of the Andean Amazon Project (MAAP) notes that the Interoceánica has converted the region of Madre de Dios to one of the deforestation hotspots in Peru, as annual forest loss has doubled in the last ten years. Examples of 2017, based on the analysis of satellite pictures,show massive forest losses particularly in two areas of the region: in the North, around the locality of Iberia, where forest roads proliferate and corn, papaya and cacao plantations and pastures have rapidly emerged along the highway (causing a deforestation of 3,220 hectares) and lands are under assaults from agricultural interests; and in the South, where gold mining activities have proliferated in the area of La Pampa and also agricultural activity has increased (causing a deforestation of about 11,115 hectares, in 2017 alone). ‘La Pampa’, located 100 km from Puerto Maldonado, is the largest illegal mining area and has among others attracted human trafficking and related crime, contributing to a lawless, dangerous site. In 2014 the Peruvian government noted that, at that point, already 40,000 ha of forest had been converted into a mining desert. This also negatively affects artisanal miners that have been operating in the area for decades without causing comparable deforestation. La Pampa is in close proximity to the Tambopata national reserve, which is also home to indigenous communities but has been increasingly invaded and destroyed by illegal miners (see EJAtlas case "Illegal gold mining in La Pampa"). The numbers feed into the general trend that indicates an increasing deforestation crisis in the region with the main drivers being gold mining, agriculture and road construction (highway as well as secondary and forest roads), revealing a close correlation between these and often illicit activities. Besides the already mentioned problematic around mining, this also indicates the immigration of landless and small-scale peasants into the lower Amazonian areas and the emergence of agribusiness along the Interoceánica. Institutions seem to weak to intervene, land right laws are loose and the legal framework for deforestation shows some clear legal loopholes (or: the influence of agricultural interests) that facilitate the progressing of the agricultural frontier. For example, Peruvian law prohibits the cutting down of Brazil nut trees (because nuts can be sold commercially) in an attempt to protect forest ecosystems, resulting in fields of papaya in which single Brazil nuts trees that have not been felled stand out; at the same time, the selling of wood without sustainability certificate has become more difficult which in turn has induced farmers to increasingly burn wood to make a profit from selling the charcoal. The legal framework moreover holds out land rights to squatters if they can demonstrate that they improved the land (e.g. after it ‘happened’ to burn down). Villagers in the North report that their region has faced several waves of land change: first through the arrival of rubber tappers and loggers, then of gold miners, now of fruit farmers, and that possibly soon land will be used by cattle ranchers.   An additional consequence of the Interoceánica is that it makes the construction of regional roads more attractive. A recent and highly controversial case is the planned road from Peruvian village Iñapari, located at the Interoceánica at the triple border with Brazil and Bolivia, to the isolated Purus region 277 km further Northeast, crossing a national park and a highly vulnerable indigenous territory. Local environmental and indigenous organizations warn that this road project would cause massive deforestation and have tremendous consequences for the affected indigenous population in the area, especially isolated, nomadic groups, possibly leading to a genocidal extermination. The road would not only increase pressure on and among communities but would most likely also trigger a proliferation of forest roads and ultimately the arrival of the soy and cattle industry, illegal logging and drug trafficking.