is the capital of the Brazilian state of Rondônia, in the
upper Amazon River basin. The population is 426,558 people (as of the IBGE 2010
census). Located on the border of Rondônia and the state of Amazonas, the town
is an important trading center for cassiterite, the mining of which represents
the most important economic activity in the region, as well as a transportation
and communication center. It is located on the eastern shore of the Madeira
River, one of the main tributaries of the Amazon River. It is also Rondônia's
largest city, and the largest state capital of Brazil (by area).