5 interesting facts about the Rio Grande River: 1 For nearly 1,200 miles, the Rio Grande forms the natural boarder between the US and Mexico. 2- The river stretches about 1,900 miles from its source in the San Juan Mountains of Colorado, down through New Mexico, and Texas to the Gulf of Mexico. 3- “Rio Grande” is Spanish for “Big River”. In Mexico, it is often called the Rio Bravo del Norte (Fierce River of the North), emphasizing its wild currents in some areas. 4- The Rio Grande supports a wid