This entry is part 2 of 10 in the series New Mexico

The Bootheel and Other Salients

Humans love the notion of organization. We’ve taken a globe and sliced it into a grid; then we filled that grid with nations, states, counties, and cities. Viewing the planet from space, our longitudinal and border lines are invisible.

Some of the lines between entities make sense, while others are completely arbitrary. If a nation lies along an ocean, the shoreline makes a natural border. On the interior of continents, other waterways supply rational borders, such as rivers and lakes. Occasionally, mountain ranges serve as borders.

Other times, however, we apply our love for straight lines to the globe. The mixture of winding, natural borders with geometric additions produces a planet-sized jigsaw puzzle.

State outlines - map by NationsOnline

Of course, borders aren’t always jollity. Countless conflicts have been waged due to lines drawn on maps.

Sometimes the human factor designs unimaginative yet geometrically pleasing shapes – see Wyoming or Colorado. Other times, strange forms emerge, weird Frankenstein amalgamations of straight edges and meandering curlicues. Ohio’s heart is half linear, half wiggle. California sports hundreds of miles of what looks like a mountainous panorama and hundreds of miles of graph-paper straightness. The panhandles of Florida and Oklahoma. The duality of Michigan. All great macro-cartographies.

Some of the most interesting quirks of the map, however, occur on smaller scales. Two states in America feature bootheels: Missouri and New Mexico. How do these strange borders come to be?

Missouri's Bootheel - graphic by Kbh3rd

Apocraphally, the nub in Missouri arose because a gentleman didn’t want to reside in Arkansas because it’s “full of bears and panthers and copperhead snakes, so it ain’t safe for civilized people to stay there over night even.” More realistically, area farmers argued the land had more in common with the land to the north than to the south, so provisions were made to keep it part of Missouri.

New Mexico’s bootheel has a much more “diplomatic” origin.

The creation of New Mexico’s borders can explain the distinct shapes of several states. Originally, the Republic of Texas looked like this:

The Republic of Texas (yellow and green) in the mid-1800s - graphic by Ch1902

The green and yellow areas above ultimately became the Republic of Texas. The blue snake of the Rio Grande looks familiar to modern viewers, while the curves of the Red River separate Texas and Oklahoma. As you can see in the graphic above, portions of Oklahoma, New Mexico, Colorado, and even Wyoming were part of the Republic. How did we end up with the unmistakable shape of Texas from this sprawling amoeba?


The Republic of Texas owed a lot of money to other entities. They needed statehood badly. As part of the process, the government of the United States took over the debt of Texas in exchange for all the portions of the above map that no longer form part of modern Texas.

Portions of these tracts became the New Mexico Territory, the Utah Territory, and a wad into unorganized sections. Thanks to the Compromise of 1850, Texas suddenly had long, straight lines to go with its meandering river borders and New Mexico started to take formation. 

Pre-Compromise of 1850 - graphic by Golbez
Post-Compromise of 1850 - graphic by Golbez

The 37th parallel formed the northern border after the Compromise and continues to do so, all the way from Oklahoma to Arizona’s border with Nevada. In the 1860s, the government split the Nex Mexico Territory in two, separating Arizona and New Mexico at the vertical line of 109 degrees west longitude. The entirety of New Mexico’s form was nearly complete.

But how did it end up getting a staircase border and a bootheel in the south?

New Mexico's Bootheel - graphic by BAlvarius

Enter James Gadsden.

As a result of the Mexican-American War that ended in 1848, the United States garnered a gargantuan swath of land between the Plains and the Pacific Ocean. Westward expansion began in earnest. One of the main goals of the nation at the time was to construct railways that spanned the continent, including one that traversed the southern portions, ending in San Diego. The easiest way to construct such a Southern Transcontinental Railway would go through land Mexico did not cede in 1848.

So, the United States decided to get more Mexican land. In 1853, the Gadsden purchase nabbed land south of the Gila River, forming the now-familiar borders of Arizona and New Mexico. The exact lines of the southern borders essentially came down to treaty negotiations. At various points, the land exchange was bigger or smaller than the final result, depending on the amount of money the United States wanted to shell out for the purchase and the prickly tactics of Gadsden.

In the end, the appropriated cash was enough to produce a bootheel.

The Gadsden Purchase - graphic by PhilFree and XcepticZP

Though the bootheel might seem to be just a tiny portion of New Mexico, it’s large enough to contain three north-south mountain ranges! The Peloncillo Mountains, the Animas Mountains, and the Big Hatchet Mountains all cram into the heel.

Geographers ascribe the word “salients” to such bootheels and panhandles. They are elongated protrusions of geopolitical entities. You can think of them as peninsulas without water. The usage of salient comes from the military term, which is an incursion made by a force into enemy territory.

The phenomenon is not limited to the United States, of course. A famous salient exists in Namibia, called the Caprivi Strip. Many others populate the globe; where politics exists, so do weird maps.

The Caprivi Strip - map by Amusing Planet
Misiones Province within Argentina - graphic by Dbenbenn
The 14 provinces of Thailand forming the salient of Southern Thailand - graphic by Ahoerstemeier

Salients, in general, bootheels and panhandles, in particular, are wonderful monikers for these cartographical intricacies. I had hoped the horn or prong portion of Texas had a specific name, but my research came up empty. Which sounds better? The Prong of Texas or the Horn of Texas?

Until we garner momentum on one of these names, we’ll have to make due with bootheels.

Further Reading and Exploration

How the States Got Their Shapes by Mark Stein

What Is A Panhandle? – World Atlas

Compromise of 1850 – National Archives

Gadsden Purchase, 1853-1854 – U.S. Department of State

How Texas Got Its Shape — And How We Celebrate It – KERA News

The History of Arizona’s Borders – Arizona State University

From Alabama to Wyoming, this is how each state got its shape – USA Today

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