Mystery of the Mexican Quadripoint

Does México have a quadripoint? That’s not intended as a trick question. Ideally this should have an easily verifiable solution. Either four Mexican states touch at a common spot — a quadripoint — or they do not. The answer however is considerably more elusive. I remain at a loss as I attempt to uncover whether someone should reasonably conclude one way or the other.

There are a couple of candidates, and the Mexican states of San Luis Potosí and Zacatecas are common denominators.

Ver mapa más grande

Notice the relative proximity of the states of Jalisco, Guanajuato, San Luis Potosí, and Zacatecas. A small notch of Zacatecas protrudes just far enough south to prevent Jalisco and San Luis Potosí from sharing a common border according to Google Maps, with all of the usual caveats about the accuracy of Google Maps. The situation seemingly separates the two states by about 1.88 kilometres (1.17 miles) according to my quick calculation.

This is an agricultural area farmed and ranched fairly intensively judging by satellite mode and confirmed by proximal Street View availability (sample image). There’s even a ranchero within the Zacatecas notch, which would be an interesting geo-oddity homestead for the lucky resident: a click east to San Luis Potosí; a click south to Guanajuato; a click west to Jalisco. It’s easily accessible from the nearest town, Ojuelos de Jalisco, less than 12km down a road called Deportiva (which translates to "sports" and runs by the town’s athletic fields as it departs town). A driver would also cross the border between Jalisco and Zacatecas a couple of times for good measure too (map).

This happy confluence of multiple borders didn’t seem to be controversial. It did in fact appear to represent two tripoints falling in very close proximity to each other. A cube of Zacatecas less than 2km on a side blocked a rare opportunity for a quadripoint.

The other potential Mexican quadripoint takes place in the vicinity of Coahuila, Nuevo León, San Luis Potosi and Zacatecas either where they all join together or where they all nearly do so, depending on the evidence one chooses to accept.

Ver mapa más grande

Google Maps sides clearly with the camp that believes in two tripoints in close proximity to each other rather than a single quadripoint, once again considering that Google isn’t the arbiter of all things geographic. However, notice the distance between to two tripoints: 12.17 km (7.56 mi). It would hardly seem to be a question with such a sizable gap. Yet, other maps are much less clear including some published by the Mexican government. The Yahoo! Group "boundarypointpoint" which specializes in just these types of situation appeared to have reached a consensus that a quadripoint did not exist, after lengthy discussions and earlier research.

However, a monument exists at what many would call the northern of the two tripoints, the "Mojonera de los Cuatro Estados" (Marker of the Four States). There are various photographs of the marker posted on the Intertubes although none that I could find with Creative Commons licensing so I couldn’t embed them here. Feel free to open a photo from Panoramio or from Flickr in another tab and observe the results. The marker would be readily accessible albeit after enduring a jarring 8.1 km (5.0 mi) ride down a rough road. I think the guy in the Flickr image with the mountain bike had the right idea.

Wikipedia bought into the idea of a Mexican quadripoint, for what that’s worth. It was presented as fact without citing any evidence, and was immediately flagged as such. Wikipedia attempted to weasel-word around the issue by stating that this is the place where the four states "effectively" meet. Right. I’m not sure de facto or close-enough provides a decent standard for a concept that implies precision. Even the contributors on boundarypointpoint seemed conflicted after the revelation of the Mojonera de los Cuatro Estados.

Examining the Mexican Geological Service website, Servicio Geológico Mexicano, provided nothing definitive and Internet searches using the Spanish-language term "Cuadripunto" yielded no better results either.

Was it a situation created by imprecise surveying techniques like the Delaware Wedge? Is it so rural and effects so few people that the governments involved simply don’t consider it enough of a priority to figure it out? Or has it been overtaken by events with a named boundary stone, the Mojonera de los Cuatro Estados, converting a close-enough approximation to an exact declaration?

In my mind, the elusive Quadripoint of México remains a mystery.

Nuevo León’s Quirky International Border

The border between the United States and Mexico has been a frequent topic of conversation and the news this summer. The Twelve Mile Circle doesn’t focus on political issues explicitly but it does have an interest in situations created by geography such as the recent border pirate phenomenon. In fact it was that situation that led me to the current topic, although indirectly.

Nuevo León en México
Source: Universidad Autónoma de Nuevo León (UANL)

I noticed something unusual as I examined the international border between Laredo, Texas, USA and Nuevo Laredo, Tamaulipas, México. There is a notch, a little chunk of the Mexican state of Nuevo León inserting itself along the international border wedged between Tamaulipas and Coahuila. The little neck is only about 15 kilometres (9 miles) wide and not much longer. However, that’s sufficient to qualify Nuevo León as one of only ten "border states" found on either side of the line, as legitimately as Texas and its 1,997 km (1,241 mi) stretch.

It’s much easier to see the notch as one drills-down within an interactive map to capture it in more detail. Follow the international border northwest out of Nuevo Laredo and it practically jumps from the image. This would be an easy pickup of three Mexican states right in a row for those who collect those types of things. Additionally, Tamaulipas and Coahuila would be neighboring states if it wasn’t for the odd Nuevo León hernia interfering with their placement.

View Larger Map

Take an even closer look at the protrusion and notice an unusual pattern of roads. The small town of Colombia appears to be platted on a typical grid but the infrastructure southeast of it looks odd. That’s because its a staging area for international trade between the United States and Mexico, more suited to warehouse space and tractor-trailers than to residential neighborhoods. Nuevo León is a highly-industrialized powerhouse of the Mexican economy with per capita GDP and income nearly double the national average. They use their little border nub as a means to move products onto the international market.

Amazingly this didn’t happen until the early 1990’s with the construction of the Colombia-Solidarity International Bridge. Nuevo León watched idly as other border states cashed-in for years. Adjacent Tamaulipas positioned Nuevo Laredo as the most important border crossing in Latin America, and the city thrived as a result. Finally Nuevo León got its bridge across to the United States and created infrastructure around the town of Colombia to capture some of that cross-border trade.

I don’t have a complete answer on how Nuevo León obtained its border notch or how neighboring Tamaulipas got its odd northwestern tentacle along the river. However, I think I might have at least a partial answer or perhaps an educated guess. I consulted the website of the ever-helpful Perry-Castañeda Library Map Collection of the University of Texas at Austin. Deep down on one of its menus lists I found a map of Mexican political divisions in 1824, created from historical sources in 1972. Assuming it’s an accurate representation, then it would follow that Nuevo León has had its river notch for close to two centuries (at least). Tamaulipas got its odd appendage because the northern third of its 1824 footprint — everything north of the Rio Grande — is now part of Texas.

That doesn’t answer why Nuevo León has river access. It merely points out that it’s been that way for a long time and predates the international border. It’s an arid area with very little rainfall so maybe the notch existed as a pathway to water. I’m speculating but I don’t know. Perhaps someone in the Twelve Mile Circle audience has greater familiarity with this topic and can use the comments section as an educational opportunity.


7 Flags Over Texas?

In a recent entry I provided a listing of the six flags that make up the famous “Six Flags Over Texas.” What is less known, and what many Texans along the southeastern border with Mexico believe, is that there were actually SEVEN flags over Texas. Had history gone a little differently this flag from the Republic of the Rio Grande would have joined the more recognizable list.

Flag of the Republic of the Rio Grande

Three sections of Mexico split away as a result of Santa Anna’s increasingly dictatorial rule: the Republics of Texas, Rio Grand and Yucatán. The Republic of the Rio Grande existed only briefly for about ten months in 1840, sandwiched between Mexico and the Republic of Texas. It was composed of three Mexican states, Coahuila, Nuevo Leon and Tamaulipas. Coahuila claimed a northern border up to the upper Medina River, and Tamaulipas up to the Nueces River. Both claims extended far north of the Rio Grande where the Republic of Texas staked its southern border. For a time this patch of land was in serious dispute, claimed by Mexico, the Republic of the Rio Grande and the Republic of Texas.

Texas Rio Grande Mexico Disputed Border

The Republic of the Rio Grande set its capital north of the river in Laredo, in what is now Texas. The Republic failed when the commanding general of its army accepted a position as a brigadier general in the Mexican army. Today there is a museum in what was once the old capitol building in Laredo.

Image of flag has been released to the public domain at

Image of the area disputed by Mexico, Rio Grande and Texas licensed under the Creative Commons Attribution-ShareAlike 2.5 License.,
cited as the original source of the edited uploaded material