Porto Velho (,
Old Port) 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 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.