During their historic journey to the Pacific, Lewis and Clark reported enormous herds of North American Bison in the midwest, so large that they “darkened the whole plains.”  Wagon trains sometimes waited days for passage through herds numbering in the hundreds of thousands, if not millions.  But by the early 1900’s the bison were reaching their low-point.  Over-hunting, drought, and encroachment on their natural habitat by humans and cattle drove the population of bison down to only several hundred animals (the actual number is disputed) — the bison were almost extinct.