Wow! Thanks for that, @blanchy! I'm going to print that and keep it as my reward for doing the research.
When driving across the middle of the US, crossing the Great Plains and even today while seeing nothing but grass (or corn, or wheat) to the horizon and imagine what it was like back in 1800 before fences and people for a thousand miles by five hundred miles; that it was one large pasture of grass, with no mountains or impassable rivers to contain the bison. It must have been the most glorious sight possible to see so many animals within touching distance of each other browsing as they walked slowly along.
I will always believe that General Sheridan's estimate of one billion bison was closer to being accurate than the 100 million he reported because he thought no one no one would believe his first estimate. That is only one animal for every eight acres; far fewer than the land would support.