Origins of the name "Poteau"
Since this question has came up numerous times, I thought I'd share a bit about it from The Birth of Poteau. In the rough draft, this section is highlighted yellow, which means that we still have to gather further information on it.
There are old stories that claim that the Poteau River was named because a group of traders stuck a stick in the ground to mark their meeting place. So far, we haven't found any truth to this claim. Usually, trappers and traders used natural landmarks to find their way, or to signify a meeting place. Based off of the evidence we do have, the description below is probably most correct.
Poteau can be translated to mean different things, depending on how the word is used: Post, Pole, Stick, Stake, and Stanchion
From the book...
...It was during this time [1700 - 1750, during the French occupation of the Louisiana Territory] that many of the landmarks in LeFlore County acquired their names. The Poteau River got its name from the French word for “Post”. When the early French explorers traveled up the Mississippi River from the Gulf of Mexico, they followed the largest bodies of water for transportation. The Arkansas River is one of the largest tributaries on the Mississippi coming from the Gulf. Most likely, the early explorers traveled down this river until they reached the point where the Poteau River diverges from the Arkansas. The French explorers and traders called this slate projection and its surrounding area Belle Point. It can be assumed that the Poteau River received its name shortly before this.
Belle Point, meaning “Beautiful Place”, had long been a popular gathering spot for trappers and traders in the area for many years. Before the area was named, it was simply referred to as the gathering spot, or post (Poteau, in French). After Belle Point was named, the smaller tributary flowing off the Arkansas River retained the original name given to the area and was subsequently named Poteau River. Another popular gathering spot for the trappers and traders was at the base of Cavanal Mountain. Cavanal means "Mountain with Many Caves".
The height of fur trappers in what would be Indian Territory lasted until around the 1830's....
"In 1718, two years before Bernard de la Harpe began his explorations, a French trading company was established under John Law for trading with the Indians." - This company focused on trapping and trading all along the Mississippi River Basin, which included the major tributaries along the river. Essentially, this began the height of the fur trading industry for the French. They would capture and skin the animals, then return down the river to New Orleans, where fur was in extremely high demand. From there, it would be shipped off to France to be resold at extraordinary prices.
Looking at the Mississippi River, it's easy to see how these traders used the main tributaries of the river as transportation routes. Remember, the waterways were untamed, so many of the rivers were much higher than they are today. Poteau River would have been wider and deeper, enabling the traders easy navigation through the area.
Fur trading remained a huge industry until around 1763. It tapered off quite a bit as France, Great Britain, and Spain vied for control of the area. France would once again claim the area in 1800, but would only keep it for three years before the United States purchased the Louisiana Territory. After that, French interests in the area died out as they focused their efforts on rebuilding after the war. The settlers that came into the area were slowly being assimilated into the "melting pot" that was the United States.
From this, we can trace back the origins of the name "Poteau". Most likely, the name originated between 1720 and 1760. Once we determine when Belle Pointe was named, then we can narrow that time frame down quite a bit. From there, we can research other places named "Poteau" in order to find similarities that will give us clues as to how Poteau was named.
During our research, we came across several places named "Poteau" or "Poteau River". A good example is Nan Poteau, Haiti, which is named after the Riviere Poteau (or Poteau River). As this river is located on the coast of Haiti, it was more than likely another "gathering spot" for French trading vessels. Another similar place can be found in Africa, as well as the many places in France.
The majority of these places contain key similarities: They stem from a large body of water; they were (or nearby) large gathering places; and they are all near easily distinguishable landmarks.
We combined this information, as well as information on how the early French hunters, trappers, and traders operated, the known history of the French in the area, and the known information about the origins of the name "Poteau" in order to determine how Poteau got it's name.
There's still more research to be done on this, but from our understanding the above quote from The Birth of Poteau is as accurate as is possible.