Brazil contains the largest share of the Amazon River basin.
The Amazon basin covers about 7 million square kilometres across several South American countries, and roughly 60 percent of it lies in Brazil. The basin is defined by the rivers that drain toward the Amazon and its tributaries, rather than by political borders.
Brazil includes the lower and central Amazon basin, along with enormous tributary systems such as the Rio Negro, Madeira and Tapajós. Peru contains much of the upper basin, while Colombia, Bolivia, Ecuador, Venezuela, Guyana, Suriname and French Guiana also contribute drainage areas.
The Amazon basin is not identical to the Amazon rainforest. The rainforest is a major ecosystem within the basin, but the drainage basin also includes wetlands, rivers and other landscapes. The Amazon River reaches the Atlantic Ocean on Brazil’s northern coast.