According to Wiki:
Thanks in part to the mercantile development associated with steam boat navigation, coupled with the internationaly driven demand for natural rubber (1880-1920), Manáos (now Manaus), Para (Brasil), and Iquitos, Peru became thriving, cosmopolitan centers of commerce and spectular--albeit illusory--modern "urban growth". This was particularly the case for Iquitos during its late 19th and early 20th century Rubber Bonanza zenith when this dynamic boom-town was known abroad as the St. Louis[4] of the Amazon.
The first direct foreign trade with Manáos was commenced about 1874. Local trade along the river was carried on by the English successors to the Amazonas Company—the Amazon Steam Navigation Company—as well as numerous small steamboats, belonging to companies and firms engaged in the rubber trade, navigating the Negro, Madeira, Purfis and many other tributaries, such as the Marañón to ports as distant as Nauta, Peru.
http://en.wikipedia.org/wiki/Amazon_River http://wais.stanford.edu/Brazil/braz...rsjr41803.html
Here's a nice virtual tour of the
Amazon Riverboats lined up in the port of Manaus