The Problem with Rivers

Rivers make terrible borders. They’re fine in the short term, but the problem with rivers is that, over the centuries, they move and change. If you’re an 18th century explorer surveying the wilderness, it’s pretty easy to come across a wide river and draw a line. But a hundred years later, when that wilderness is a bustling metropolis, a slight shift in the flow of the river could cause border disputes worth millions. It can also cause other bizarre problems, like “islands” of land attached to the wrong state. Here are a couple of the odder quirks of shifting waters.

The Mighty Mississippi

The Mississippi is one of the world’s biggest and most powerful rivers. After the American Revolution, it formed the western border of the new United States. It still exists as the border between the east and the west. For example, it separates the suburban hills of St. Louis from the rural floodplain of southern Illinois. But 80 miles south of the city, there’s a town called Kaskaskia. It’s technically in Illinois (serving for a time as the capital), but it’s on the Missouri side of the river.

When Kaskaskia was founded, it was a bustling boom town on a prominent peninsula. But in 1881, a great flood destroyed the city and shifted the river a couple of miles to the east. However, the man-made border did not move with it. Today, Kaskaskia is an Illinois exclave with a population of 14. Thanks to the Big Muddy river, it is just a footnote in history.

The Rio Grande

Since Missouri and Illinois are both part of the US, Kaskaskia’s position isn’t a big deal. The same can’t be said for the tracts of land along the Rio Grande. As a large part if the border between the US and Mexico, the Rio Grande’s shifting banks can have dire international consequences. On at least four separate occasions, the river has cut of a parcel of land from Texas. One of these was claimed by New Mexico, with the other three claimed by Mexico. In the three international incidences, treaties were signed ceding the orphaned strips of land to Mexico. On the other hand, in the domestic dispute between Texas and New Mexico, the Supreme Court sided with Texas, creating a swath of El Paso on the “wrong” side of the river.

The Delaware River

Delaware Shore logo

It may look like New Jersey, but that river bank belongs to Delaware.

Borders don’t just cover land. Water rights are important too. Most rivers are split down the middle. Specifically, they are split at the deepest part of the channel, which is called the Thalweg (German for “valley way”). But not every river is divided on the Thalweg. In 1681, King Charles II defined a 12-mile circle around the courthouse in New Castle. This circle cut into an existing part of New Jersey. As a compromise, New Jersey took a “bite” out of the circle, and Delaware got the water rights to that entire part of the Delaware River.

Because of the wording of this ruling, Delaware controls the entire river up to the shoreline. This has caused problems for factories on the Jersey bank, who were sued for infringing on Delaware waters. As recently as 2008, the Supreme Court ruled in Delaware’s favor, all because of the wording used by King Charles.

The Hudson River

The Thalweg principle was also ignored up in the New York Harbor, at the tail end of the Hudson River. Again, the problem dates back to colonial times. New York had settled several islands on the New Jersey side of the Thalweg, and as a compromise, they came up with an odd split, where New York got the land and New Jersey got the water. (Oyster fishing was big business back then, so this was a good deal.) But like so many other river borders, this compromise grew more complicated with time.

On a little speck of land called Ellis Island, New York built an immigrant processing center. As the number of immigrants grew, so did the island. New York added landfill to make the island bigger. A century later, with Ellis Island turned into a museum, New Jersey sued. They claimed that New York only had the rights to the natural part of the island. The Supreme Court agreed, and all of the reclaimed land became part of New Jersey. This border cut through buildings and rooms, so both states share jurisdiction over the whole island. Still, it goes to show the problem of using rivers and shorelines for borders.

Using rivers as borders shows how short-sighted we are as a species. What looks like a permanent fixture of the landscape is just a temporary stream on the geological scale. It’s amazing how much things can change in a century.

Steve Lovelace

Steve Lovelace is a writer and graphic artist. After graduating Michigan State University in 2004, he taught Spanish in Samoa before moving to Dallas, Texas. He blogs regularly at

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5 Responses

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