Manaus, Brazil, is the largest city in the basin, with a population of just over 1.6 million. Manaus is the capital of Brazil’s largest state, Amazonas, and is a major trading center for the region. When the Amazon basin was the only known source of rubber, Manaus experienced a boom, but subsequently declined in importance due to the planting of rubber in other regions of the world. Manaus has since recovered by becoming a duty-free trade area of 1.6 million people.