BDKJMU wrote:https://www.ndsu.edu/news/view/detail/36952/According research team, there may be a historical factor in all this. Bison is a French word pronounced “Bee-zohn,” and our pronunciation may have its roots there, going back generations to the area’s early fur traders and explorers. “Winnipeg has a significant French influence, so it’s very possible we borrowed from them. That would also explain why hardly anyone else in the U.S. says it that way,” Barta said.
Of course hardly anyone else in America pronounces it that way. Most of the rest of America don't pronounce things like faggity ass Frenchmen.
There was a large population of French descendants in ND (The Metis) running part of the fur trade that the name is probably a holdover from.