Borders and Barriers: The Geography of Boundaries

November 21, 2022

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When we take out-of-town visitors or students from Southern Oregon to Lava Beds National Monument in far Northern California, we usually stop at the State Line Store, taking paved county roads. When we get out, they are surprised when I say, “Welcome to California.” On these roads, there are no signs nor any markers. I point across the road and tell them, “That’s Oregon; we’re standing in California.”

That boundary is invisible, except for the road, but real. North of this boundary, you don’t pay sales tax; here at the store, you do. Boundaries define many aspects of our life, from our local area, as above, to global geopolitics. But what is a boundary, how is it defined, and who defines it? In this article we’ll explore some of these questions.

What Is a Boundary?

Of course, we are talking about geographic boundaries, not personal boundaries, obviously, and in some way or another, all boundaries on earth are defined geographically. Some are “hard,” meaning you are on this side or the other side, like most national borders. Some are soft, not clearly defined, like traditional indigenous lands or ecotones.

They can be empirically defined or amorphous. They can be clear divisions, or they may overlap. Below, we’ll explore examples of all of these.

 Whose Land Is It?

Some of the most obvious examples of hard boundaries are national boundaries, and in the U.S., state boundaries. These boundaries range from colonially-defined boundaries in Africa and the Middle East to the current European boundaries, defined by centuries of war and turmoil.

In 1884, at the Congress of Berlin, Africa was divided among 15 European powers, creating most of the borders that still exist today, as shown in this interactive map of colonial Africa. These boundaries were not based on any knowledge of the people living there, but the interests of these powers for resource extraction and transportation, particularly access to sea routes. (Notice all of the straight lines, then…)

Compare that map with one showing pre-colonial conditions. As with many traditional, non-Eurocentric cultures, nations were defined primarily by languages, as shown in this interactive map. I couldn’t find one single map that overlaid both sets of boundaries, but for advanced level students, it could be a good final project. The modern-day boundaries can be downloaded from various sites, including ArcGIS Online and the CIA World Factbook. Finding the language areas as GIS data would be more challenging, but advanced students would surely be up for the challenge.

These boundaries have led to many conflicts, where ethnic nations were separated between nation-states, or else forced together in one state with conflicting nations. The Rwandan genocide is but one tragic example of this misguided arrogance.

American colonialism, an off shoot of European colonialism, has its dark side as well. Look at any contemporary atlas and you’ll see mostly straight lines west of the Appalachians, except where rivers come into play, and in the East, more squiggly lines but still many straight ones. The same is true of our neighbor to the north, Canada, where you will also see many straight lines, especially in the prairie provinces and, of course, on the international boundary with the U.S.

However, the first inhabitants of our beautiful continent didn’t follow straight lines, nor were there hard boundaries. There was not necessarily an “our side vs. your side” view of the land. That’s not to say that there were no conflicts over territory. Sometimes it was contested, sometimes it was shared, but all of us in North America live on native land.

The Canadian nonprofit, Native Land Digital, has made a fascinating interactive map of indigenous territories. It shows traditional indigenous territories across the globe, but the Americas are the most comprehensive ones. As you hover over any place on the map, you’ll see information on each of the territories, and even at first glance, you can see that many of the territories overlap. There are toggles to show languages and treaties, as well as tribal areas.

Although rich in data, the site is based on Mapbox and OpenStreetMap, so it is open to community contributions, and therefore, does not claim to be authoritative in any way. The territories are subject to much interpretation and reflect spatial boundaries which have been fluid over many centuries.

Boundaries of Conflict

Boundaries are drawn and re-drawn for many reasons. Sadly, one of the reasons is war. In these situations, the winner draws the new boundaries. The national boundaries of Europe have changed countless times over the last 2,400 years, as shown in this fascinating (but long) animated map, which also offers a thundering soundtrack with horns and tympanies.

In modern times, some of the truly “hardest” boundaries in the world are those in Israel and occupied Palestine, specifically the Gaza Strip and the West Bank territories. The history of this centuries-long conflict is too complex to address here, but it has significantly affected global geopolitics, especially in the late 20th and early 21st centuries. Using Mapbox, the Israeli nonprofits, B’Tselem and Forensic Architecture, have built an amazing map of the conflict in the 20th century, focusing on the fragmentation of Palestinian territories by Israel.

Meanwhile, Back in the U.S…

After the field season ended in late August, I was tasked with processing soil samples at the BLM headquarters on the outskirts of Anchorage. It was tedious but fun — moose would wander by, and eagles flew over, as did helicopters. On my way to return samples and get more, I always passed the cadastral division. It wasn't just a room; it was a complex. I was an archaeologist then, not a geographer, so the maps on the walls didn't make much of an impression. What I did notice was rows on rows of filing cabinets and horizontal map cases, all containing the cadastral maps for this enormous state.

As the European powers did to Africa, so did the Americans to the United States, albeit more systematically. We are all familiar with the PLSS of township-range-section, which divides most of the nation into nice one-mile squares. Some places in the Southeast, the original 13 colonies, and some southwestern states don't follow this, however. The 13 colonies divided land in ways that are too complex to discuss here, while the Southwest states have a legacy of Spanish land grants, and in Wisconsin, the French system of long narrow lots, all with water access, defined several areas.

If you are a true geo-geek, you can see the PLSS of the entire U.S. on an AGOL map. When you zoom in to the quarter-section level, you can get more detailed information. It's also fun to see the satellite imagery in great detail. And for fun and informative reading, I highly recommend “How The States Got Their Shapes” by Mark Stein.

As I mentioned above with Africa, it would be an interesting project for students to take the maps from Native Land Digital and overlay them on the PLSS system.

Boundaries Invisible yet Real

Other than “Welcome to Oregon” and 47 other signs, (Alaska and Hawaii don’t need to tell you where you are) state lines in the U.S. are generally invisible, except when you cross the “Mighty Mississip” between Illinois and Missouri, or other river boundaries. A professor told me that rivers make terrible boundaries because they are so dynamic. Look at a gorgeous lidar image of the lower Mississippi by Dan Coe to illustrate this point.

Invisible yet hard boundaries exist not only on land but also at sea and in the air. By United Nations treaty, every nation has a 200-mile Exclusive Economic Zone, which can be viewed on the Marine Regions site in an interactive map.

No-fly zones are another example. In most cases in the US.., they are established zones for the safety of civilian air traffic. Recently, however, they have been established for drones, especially on wildland fires. The U..S Forest Service even has posters of “If You Fly, We Can't.”

Where Are the Next Boundaries?

Like every other continent, Antarctica has been carved up into territorial claims by powerful nations, some of which overlap. Theoretically, there are to be no permanent settlements, but as history has shown, treaties are made to be broken.

When we colonize the moon and Mars, who will determine the boundaries, and how? Several treaties have been signed and proposed, and are subject to much discussion. Will they be honored, or will it be first-come, first-serve, as was the colonization of the Americas? As far as we know, there are no sentient cultures to be subjugated in space nor Antarctica. Hopefully the penguins won’t object. Or maybe… they should be the ones in charge.


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