The Brazos River rises at the confluence of its Salt Fork and Double Mountain Fork near the eastern boundary of Stonewall County (at 33°16' N, 100°01' W) and runs 840 miles across Texas to its mouth on the Gulf of Mexico, two miles south of Freeport in Brazoria County (at 28°53' N, 95°23' W). The two forks emerge from the Caprock 150 miles above the confluence, thus forming a continuous watershed 1,050 miles long, which extends from New Mexico to the Gulf of Mexico and comprises 44,620 square miles, 42,000 of which are in Texas. It is the longest river in Texas and the one with the greatest discharge. It has all of the varied characteristics of a trans-state stream, from the plains "draw" drainage through canyons at the breaks of the Llano Estacado, the West Texas rolling plains, and the Grand Prairie hill region, to its meandering course through the Coastal Plain. The elevation of the streambed at the confluence of the two forks is 1,500 feet above sea level. From this point the Brazos descends to the Gulf at a rate diminishing from 3½ feet a mile to one-half foot a mile.
Below the Caprock escarpment the Brazos traverses an area of rolling topography in the vicinity of Palo Pinto County, where low escarpments cross the watershed and the basins of the Brazos and its tributaries are deeply trenched and confined in narrow valleys with steep sides or bluffs. The floodplains are narrow, and improvements came slowly and comparatively late. When the river reaches the escarpment that crosses the watershed on a line from Georgetown to Waco, the topography changes to gently rolling, then to an almost featureless plain down to the coast. In this portion the river and its tributaries flow through much less rugged terrain, and stream valleys are wide and flat. Here the floodplain became highly developed rather early in Texas history. The Brazos has seven principal tributaries, including the Salt and Double Mountain forks. The others are the Clear Fork, the Bosque and Little rivers, Yegua Creek, and the Navasota River. In addition, there are fifteen subtributaries within the watershed, the most important being the Leon River, a tributary of the Little.
The Brazos is probably the river that Indians of the Caddoan linguistic group called Tokonohono. This name is preserved in the narratives of the expedition led by René Robert Cavelier, Sieur de La Salle, and the Brazos is widely identified as the river that La Salle named the Maligne. The name Brazos was probably first applied to the Colorado River, and there is considerable evidence that several early explorers got the Colorado and the Brazos rivers confused. In 1716 Isidro Félix de Espinosa and Domingo Ramón probably called the Brazos "la Trinidad," but the present names were established well before the end of the Spanish period. The full name of the river, often used in Spanish accounts, is Los Brazos de Dios, "the arms of God." Many legends have grown up explaining the name. Probably the earliest is that Francisco Vázquez de Coronado and his men wandering up the Llano Estacado were about to perish from lack of water when the Indians guided them to a small stream, which the men then named Brazos de Dios. Another account tells of a Spanish ship tossed about by a storm in the Gulf of Mexico that had exhausted its supply of drinking water. The sailors were parched with thirst, lost, and unable to determine which direction they should go to find land, when one of the crew noticed a muddy streak in the waters. The ship followed the streak's current to the mouth of a wide river on a great rise. The ship sailed up the river, and the sailors drank fresh water and were saved. In gratitude they christened the unknown stream Brazos de Dios. Another account fixes the naming of the stream in the 1760s, when an extreme drought made it impossible for the Spanish miners on the San Saba to work. They had heard that the drought was even worse toward the south. They headed toward the Waco Indian village where, according to reports, there was a never-failing stream. Many of the men and beasts died en route, and the precious bullion was buried, but the few who finally reached the stream named it Brazos de Dios. The last story, told to Albert Pike in 1831, accounts for the reversal of the names of the Colorado and the Brazos.
Although the Brazos was well known to Spanish explorers and missionaries who described the Indians along its banks, the first permanent settlements on the river were made by Anglo-Americans. John McFarland, one of the Old Three Hundred, founded San Felipe de Austin at the Atascosito Crossing of the Brazos. The town became the colonial capital of Texas. The river acquired further significance as being, at Velasco, the scene of the first colonial resistance to Mexican authority, and, at Columbia and at Washington-on-the-Brazos, the site of two of the first seats of government of the republic. Cotton and sugar plantations established along the Brazos in pre-Civil War days were showplaces of Texas and homes of some of the wealthiest men in the state.
The climate of the Brazos watershed varies considerably from temperate to subtropical. The average annual temperature is 59°F in its upper reaches and 70° in the coastal region. Normally, the winters are mild and short, even in the upper reaches, but severe weather is not unknown. Temperatures of zero and even lower have been recorded. The average annual rainfall is 29.5 inches, ranging from sixteen in the northwest to forty-seven in the southeast. Soil types along the Brazos vary from sandy loams to deep clay. A variety of natural vegetation ranges from scattered oak mottes and bunch grasses in drier areas to conifers and hardwoods in areas where rain is plentiful. Virtually the entire area of the watershed is suitable for some form of farming or ranching activity. The most important products of the region have been cotton, cattle, and oil.
Originally, the Brazos was navigable for 250 miles from the Gulf to Washington. It was an important waterway before the Civil War, and efforts to improve it for navigation continued until the early twentieth century. The most important cities in the Brazos watershed are Lubbock, Graham, Waco, Temple, Belton, Freeport, and Galveston. Houston abuts the region along the Fort Bend and Brazoria county lines.
The waters of the Brazos basin are administered by the Brazos River Authority, an autonomous state agency established by the legislature in 1929. In later years the Brazos has maintained its importance as a source of water for power, irrigation, and other services. The river has been dammed in several places to form reservoirs for flood control, municipal use, and recreation, the most important of these man-made lakes being Possum Kingdom and Whitney reservoir. In Goodbye to a River (1960), John Graves gave an account of his journey in a canoe down the Brazos in the mid-1950s, with historical sketches of Indians and pioneers.