Mexico’s northern borderlands have become notorious for their lawlessness. At times it can seem that organized crime groups have as much control as the federal government. Last year was actually Mexico’s most murderous year on record. The drug trade is the easy and obvious explanation for this phenomenon, and it isn’t wrong – but it is incomplete.

Mexican governments have always had a difficult time ruling over the outer reaches of their domain. The Spanish Empire, which also had the capital of its Viceroyalty of New Spain in Mexico City, had similar issues. The Aztec Empire (also based in Mexico City, though it called it Tenochtitlan) would have encountered the same problem if it had gotten much larger. The common thread here isn’t narcotics; it’s geography. The region around Mexico City is the heartland of Mexico, but it’s also disconnected from the farthest reaches of the country by distance, mountain ranges and plateaus.

This Deep Dive will take a closer look at the features of Mexico’s geography that make its borderlands and peninsulas so difficult to control from the center. We’ll also look at Mexico’s history, which is rife with periods that promoted the localization of security and independent-minded regional security forces. And we’ll discuss the northern border region and its relationship to the U.S., specifically what it would take for the U.S. to intervene militarily to secure the border and quell the violence.

Geography Then and Now

Mexico City, the seat of Mexico’s government, has a very basic problem: It has a lot of territory to govern and many physical obstacles between itself and much of that territory. Mexico is one of only two places in the world (the other is off the coast of Peru and Ecuador) that resides on or near the junctions of four tectonic plates – the Pacific, Cocos, Caribbean and North American plates. This makes the country a hub for seismic activity, the cause of Mexico’s many mountain ranges and plateaus. The mountainous topography separates the country into regions with unique physical environments. In some areas this hindered the development of population centers, and it has defined the culture as well as which economic activities are viable.

Narrow coastal plains and basins run along either side of the country. To the extreme northwest and southeast are the Baja California and Yucatan peninsulas, respectively. Just a short distance inland, three mountain ranges flank the mainland – the Sierra Madre Occidental in the west, the Sierra Madre Oriental in the east, and the Sierra Madre del Sur in the south. Between the western and eastern mountain ranges is the massive Mexican plateau.

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Geographically, the Mexican plateau is a single feature; geopolitically, there’s a clear division between the northern and southern plateau regions. The Chihuahuan Desert dominates the northern plateau. It does not easily support large-scale vegetation, wildlife or human populations. The southern plateau, on the other hand, sits at an altitude 3,000 feet (900 meters), which gives it a much more habitable climate, and its valleys to the south are among the most habitable in the country. Temperatures in the southern plateau and valley average 40-80 degrees Fahrenheit (about 4-27 degrees Celsius) year-round and rarely reach extreme levels. Annual rainfall is typically about 28 inches (71 centimeters), well above the roughly 15 inches needed to maintain agricultural practices, and arable land makes food production possible.

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Put these factors together and it makes sense why the valley south of the southern plateau region is the heart of Mexican civilization – the center of the Aztec empire and still the geopolitical heartland of the country today. The coast could support a large population, but any capital there would have found itself even more disconnected than Mexico City is from the rest of the country. The southern plateau isn’t perfect, but it is the best chance a civilization has to expand and project power to all corners of modern-day Mexico.

In fact, a glance at the pre-Columbian empires – mostly the Aztec but also the Mayan – provides a blueprint for understanding how Mexico’s mountain systems still impede power projection today. Both civilizations reached their limits in large part because of the difficulties that came with regularly traversing mountain ranges. For the Aztec, administrative systems were put in place to reflect this. The Aztecs’ capital was Tenochtitlan, modern-day Mexico City. As their empire expanded, direct control over their new holdings did not. In some areas they allowed local officials to govern and demanded tribute in return.

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Nearly 500 years have elapsed since the Aztec Empire fell, but the situation isn’t all that different for Mexico today. Technology has reduced geography’s impact, but rarely does innovation overcome geography entirely. The mountains and long distances that afflicted the ancient empires of the land are still making it hard for the government in the valleys off the southern plateau to have a strong presence in Mexico’s peninsulas, coastal regions and northernmost states.

The Monumental Task of Unification

Mexico’s topography poses the same challenges to internal security that it does to central governance. Historically, Mexico City could not easily move large numbers of troops over vast distances and treacherous terrain, so it has had no choice but to rely on local forces to augment the national security forces. The Mexican states, in turn, have been conditioned to be self-reliant on security. From time to time, the isolation of some areas and subsequent feeling of alienation has engendered the creation of armed rebel groups hoping to secede from or even overthrow the national government. Combined, these trends have led to a strong belief in homegrown security and skepticism of the national government. This strongly influences the way the state and non-state actors respond to lapses in security in modern Mexico. Where geography and estrangement once fostered rebellion and independence movements, today those factors help explain the rapid growth of organized crime groups and the vigilante groups that have popped up to stop them.

The reliance on local forces to augment central government forces dates back to Mexico’s colonial period, though initially it had less to do with the region’s terrain or vastness. Throughout the 17th and 18th centuries, Spain was engaged in multiple wars across Europe. The Spanish crown needed its troops for battles in the near abroad, and so once Mexico was considered conquered, Spain redirected military resources to its European endeavors. Much of the day-to-day security responsibilities were put in the hands of the colonists and local authorities. Mayors and business elites often funded irregular militias to help enforce security in the countryside and city centers.

Over time, Spain sent more regular troops over to Mexico, but mostly it tried arming and training locals to enforce security. By the early 19th century, near the start of Mexico’s war for independence, there were approximately 40,000 security forces in Mexico, only 6,000 of which were professional soldiers. The rest were from local militias. When Mexico’s independence movement took shape, it drew most of its fighting force from those local militias.

Once Spain was driven out, however, Mexico still faced the monumental task of unification. Many states were reluctant to answer to a central authority immediately after ridding themselves of Spanish rule. As a colony, economic activities had been poorly integrated – the states’ focus had been on shipping goods to Spain, not to each other. And the states had their own longstanding militias, whose members often had a strong affinity for their local authorities.

As a result, the newly formed Mexican government spent much of the 1830s and 1840s confronting secessionist movements. The central government was ill-equipped to deal with so many threats at once. Many state and local governments refused to pay more taxes and support a national army, preferring instead to maintain their own forces for defense. Large-scale rebellions erupted in Zacatecas and Tabasco, while republics temporarily formed in the territories of Texas, Yucatan and Rio Grande. (Texas eventually joined the United States, Yucatan returned to Mexico, and Rio Grande split the difference – part went to Texas, the rest became the Mexican states of Coahuila, Nuevo Leon and Tamaulipas.) Not coincidentally, all the areas where republics formed are far from the southern plateau region, and mountain ranges or deserts separate them from Mexico’s core.

Later in the 19th century and into the 20th century, other political shifts reinforced the idea that local security forces must have a prominent role. When the French tried to re-establish a monarch in Mexico in 1861, some Mexican elites endorsed the effort. Much of the country didn’t. France sent its military to impose its will. Local forces had to be commandeered to fight the French national troops. During the French intervention, the ousted Mexican government still strove to function in parallel to the French and was never fully quashed.

Then in 1910 came the Mexican Revolution, when the idea of local force development was even more vital to the revolution’s success. The longstanding government of President Porfirio Diaz used patronage to build close ties with local leadership and used the military to crush dissent. Though this approach succeeded in bringing economic growth and the most stable government structure the country had seen up to that point, it was unsustainable. Many segments of society lacked input or representation in government, and eventually they fought back.

The revolution gave a voice to the miners and farmers and factory workers who had been voiceless under the elitist government. When it came time to write a new constitution in 1917, more power was given to the local authorities. The new constitution provided a framework for security and conflict resolution under the guidance of local community leaders.

Modern Mexico

A century later, the most vexing areas for the Mexican central government are those in the northern part of the country because of their proximity to the United States.

The U.S.-Mexico border stretches almost 2,000 miles (3,100 kilometers), long enough for distinct sections to develop. A 2011 Foreign Policy Research Institute report provides a geopolitical breakdown of the border and surrounding region into three parts. First, there is Baja California, which consists of Mexico’s Baja California and Baja California Sur states (bordering California). Then there is the central band of the border referred to as the Sierra Madre, which includes Sonora and Chihuahua states (bordering Arizona, New Mexico and west Texas). The northern sections of Durango and Sinaloa are essentially part of this border section, though they don’t actually border the United States. Finally, there’s the Rio Grande Basin, which sits just south of Texas and includes Coahuila, Nuevo Leon and Tamaulipas as well as the northern parts of Durango, Zacatecas and San Luis Potosi (which, again, aren’t on the border but are so connected to the border states that they may as well be).

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Economically, some of these states are as connected, if not more connected, to their neighbors to the north than they are to the people in the southern plateau who govern their lives. These are realities that Mexico can live with, but the violence and insecurity of the northern states are a different story. Mexico City cannot let the situation deteriorate to the point that it loses the ability to exert authority, or even worse, that the U.S. feels compelled to intervene.

Baja California is strategically valuable for Mexico as a natural land buffer along the Pacific coast. Much of the peninsula, and its population, is closer to California than it is to Mexico City. As a result, the peninsula boasts strong cross-border ties with the U.S., and American companies have been influential in the region’s development. On the Atlantic coast, the Rio Grande Basin provides its own strategic value given its proximity to the Gulf of Mexico. Its local businesses are closely tied to the Texas economy, which is as important, if not more so, to the local livelihood as Mexico City.

The Sierra Madre region in the center is one of the most difficult regions for Mexico to control. It includes mountainous terrain on either side, with the vast Chihuahuan Desert in between. This was one of the least populated areas during the colonial and early independence times. Because of the terrain, ties with Mexico City are meager, and it is difficult to sustain population centers. These conditions bred a strong feeling of distance from Mexico’s central government. Once upon a time, clashes with indigenous groups like the Comanche were frequent, and a distinct rancher and cowboy culture took root, which contrasted sharply with the cosmopolitan, aristocratic society of the capital. Mexico’s wars have also had a large impact on the people of this area. During the war for independence, Spain severed Mexico City’s supply lines to the north, and Sonora state suffered as a result. Inhabitants of the area were also the most affected among Mexicans by the exchange of territory at the end of the Mexican-American War.


Mexico’s government today faces the same challenges in projecting power as those that came before it. Its ability to influence the outer reaches of the country dwindle with each mile and mountaintop, same as ever. The difference today is that the actors filling the power void aren’t concerned with self-governance; they’re organized crime groups fighting for turf, and vigilante groups fighting for peace. After so many instances in which local populations benefited from taking matters into their own hands, there is a sense of local entitlement to self-governance. The result has been widespread violence, the deterioration of local institutions and a central government looking more and more to the military to re-establish law and order.

As the violence creeps toward and exceeds historic levels and uncertainty grows about the government’s ability to control it, the U.S. is paying close attention to the potential for spillover. It’s not unheard of that the U.S. would react to security threats emanating from across the border: Instability during Mexico’s revolution provoked a U.S. military intervention in 1916, when the U.S. Army sent a “Punitive Expedition” force to capture Pancho Villa.

But if that’s what it takes for the United States to intervene, we are a long way from intervention. At the time of its revolution, Mexico’s central government was extremely weak, and multiple border incursions had resulted in the killing of U.S. citizens on U.S. soil. Before Washington got involved, it pursued other measures such as putting more troops on the border, declaring martial law along the Texas border and setting up blockades to prevent arms shipments from reaching Mexico. Today, its focus is on building a wall.