OP discovers river lots. Lots like this are an old design, that allowed everyone access to the river while giving you a decent amount of land. They are very common in Ontario, and such.
They are also a fucking nightmare if you're doing any sort of survey in the area, that requires land access because for a given area, you now have to negotiate with 350 land owners instead of like 30.
This seems a bit egregious for a lot, it's just over 50 ft wide and nearly a mile and half long. It looks more like a developer made the "lot" to develop the rest of the nearby homes then managed to get a house built on it.
I get it, but there's a logic to it being so long if you think about it: flooding. You want river access without risking your house getting washed away. As I said, it's an old lot layout method - like from the mid 1800s or earlier, with ties to how things were laid out in France originally.
Louisiana? I’m guessing that before the Louisiana Purchase, they had similar non-primogeniture-based inheritance laws to Quebec, resulting in properties being divided into ever-thinner strips with each generation.