Rio Branco (White River) is a Brazilian city, capital of the state of Acre. Located in the valley of the Acre River in northern Brazil, it is the most populous county in the state, with 305,954 inhabitants – almost half the state population, according to a 2009 estimate.
Rio Branco was one of the first settlements to appear on the banks of the Acre River. In 1913 it became a county. In 1920 it became the capital of the territory of Acre, and in 1962, the state capital. It is the administrative center for the economic and cultural region.