Internal or within-state migration is common in Africa and elsewhere and has environmental and social consequences that are often poorly understood. We conducted a national-scale study tracking the movements of agropastoralists in Tanzania and documented the extent of associated environmental changes. The data were drawn from interviews with government officials in 80 rural districts covering the majority of land area across the country. According to interviewees, recent settlement is associated with forest clearing, overgrazing, and landscape burning. Conflicts such as lion killing and forced evictions of settlers often occur. Our interview data uncover limited capacity and lack of coordination among different levels of government to deal with these challenges. The novelty of our study is in its ability to draw on reports from ground-level administrators and to aggregate this information in order to both describe the impacts of rural migration over a large area and inform appropriate policy action from national-level decision-makers.