Largest river between the Red and the Rio Grande, the 840-mile Brazos rises in 3 forks: the Salt, Clear and Double Mountain forks. According to legend, this river saved Coronado's Expedition of 1540-1542 from dying of thirst, so the men thankfully named it "Los Brazos de Dios" (Arms of God). On its banks were founded historic San Felipe, capital of Stephen F. Austin's Colony, and Washington, where in 1836 Texas' Declaration of Independence was signed. Vast plantations thrived in the fertile Brazos Valley, making cotton "king" in Texas until the Civil War.