The Brazos proper begins at the confluence of its Salt Fork and Double Mountain Fork (which rises west of Lubbock and passes through the town). Its main tributaries are the Clear Fork of the Brazos, which passes by Abilene and joins the main river near Graham, Bosque River, Little River, Yegua Creek, and Navasota River.
Initially running east towards Dallas, the Brazos turns south, passing through Waco, then by Bryan and College Station, then southwest of Houston near Richmond, and into the Gulf in the marshes just south of Freeport.
The Brazos is dammed in two places, both north of Waco, forming Lake Granbury and Lake Whitney.
It is unclear as when it was first named by European explorers, since it was often confused with the Colorado River not far to the south, but it was certainly seen by La Salle. Later Spanish accounts call it "Los Brazos de Dios" (the arms of God), for which name there were several different explanations, all involving it being the first water to be found by desperately thirsty parties.
While the river was important for navigation before the American Civil War, it is primarily important today as a source of water for power and irrigation. The water is administered by the Brazos River Authority.