One of the more confusing aspects of the geography of the Southwest is the fact that there are two completely different rivers with the exact same name, and they’re quite close to each other. The name is “Rio Puerco,” meaning “dirty river” in the New Mexico dialect of Spanish. It’s an apt name, since rivers in the area tend to carry a lot of sediment and the water in them tends to look rather dirty. Nevertheless, the use of it for both rives can lead to considerable confusion, and while in technical and scholarly contexts they tend to be carefully distinguished, in more accessible public contexts there isn’t much clarification out there.
One Rio Puerco originates in the Jemez Mountains and flows south through the village of Cuba, then parallels the Rio Grande for a considerable distance before joining it south of Belen. In contexts where careful disambiguation is necessary this river is generally called the Rio Puerco of the East, on maps and signs where highways like US 550 cross it it’s usually just labeled “Rio Puerco.” Today the Puerco of the East forms a rough eastern boundary for the Navajo culture area, and the communities along it (especially Cuba) serve as important points of contact between the Navajos and the New Mexico Hispanic culture area.
The other Rio Puerco originates on the southern slope of Lobo Mesa near the Continental Divide and flows generally southwest through Gallup and the Red Mesa valley, paralleling the railroad and I-40 into Arizona. It passes through Petrified Forest National Park before flowing into the Little Colorado River at Holbrook. This river is generally called the Rio Puerco of the West, and it forms a very rough southern boundary for the Navajo culture area, with the area further south dominated by the Zunis along the eastern portion and by Anglos (largely Mormons) along the western portion. The towns along the river are mostly nineteenth-century railroad towns.
Clearly, these two rivers are very different and have nothing to do with each other. They are on opposite sides of the Continental Divides and belong to completely different drainage systems: the East flows into the Rio Grande and ultimately into the Gulf of Mexico, while the West flows into the Little Colorado, which flows into the Colorado just upstream from the Grand Canyon and ultimately ends up in the Gulf of California. Confusingly, though, they’re really quite close. If you drive from Albuquerque to Flagstaff on I-40 you cross both of them, and each is marked only by a sign saying “Rio Puerco.” They are also both close to Chaco, and both areas were integrated into the Chacoan system, though probably to different degrees. The only major Chacoan site known from the Puerco of the East is Guadalupe, while the Puerco of the West has a whole string of sites that have been identified relatively recently as Chacoan outliers, including Allentown, Chambers, Sanders, and Navajo Springs. Unfortunately, the names are so entrenched at this point that there’s little prospect of changing either (or both) to something less confusing, so it looks like this is something we’ll just have to keep dealing with. Hopefully this post will help reduce the amount of confusion over this issue.