This study aims to show, in the environmental history perspective, aspects related to the nature of the Tocantins River,the socioeconomic relations, cultural values and the riverside population’s lifestyle in the 20th and 21st centuries. This analysis is made through the study of two cities: Imperatriz (MA) and Porto Nacional (TO). Its aim is to notice the spatial, environmental and socioeconomic transformations experienced by these cities. Furthermore, we intend to analyze, in a comparative way, the impacts related to the construction of the Belém-Brasília highway, the North-South and Carajás railways, the hydroelectric dams and the Araguaia-Tocantins waterway.