The Teles Pires (Portuguese: Rio São Manuel) is a 1370 km long river in Brasil.[1] The river flows through the state of Mato Grosso and its lower part marks the border between the states of Mato Grosso and Pará. At its mouth it joins Juruena River and together they form the Tapajós, which is one of the biggest tributaries of the Amazon River. The most important[citation needed] settlement along the river is Alta Floresta.