Río Bravo is the southernmost region of the territory, and borders the regions of Cholla Springs to the northeast and Gaptooth Ridge to the northwest. A large portion of the southern border is defined by the San Luis River. Travel through the area is also extremely hazardous, due to the frequent cougar and wolf attacks that occur, particularly in the higher altitudes. Río Bravo seems to be based off southern New Mexico and Western Texas, especially areas such as the Guadalupe Mountains and Chihuahuan Desert.
The area is also sparsely populated compared to the other regions of New Austin, probably due to the absence of major settlements and/or towns.
This is the only region in the game in which the player cannot purchase a safehouse. However, there is property in Plainview which the player can rent for $5 a night ($10 if Abner Forsyth was spared in The Prohibitionist).
Rio Bravo is also a town in Texas that was established before the game takes place.
In Red Dead Redemption, Benedict Point is located in Gaptooth Ridge. In Red Dead Redemption 2, it is in Río Bravo instead.
Río Bravo is one of the few regions to be confirmed to have county status, the other is Lemoyne's Scarlett Meadows. It is mentioned to be a county by Marshal Leigh Johnson in Political Realities in Armadillo.