In order to deny Native Americans the staple animal that sustained much of their lives, in the 19th century, the U.S. government sanctioned and supported the slaughter of tens of millions of bison by settlers and soldiers, reducing 60 million (est.) animals in the late 18th century down to just 541 animals by 1889.
Two illustrative quotes from the Wikipedia article on American bison hunting:
-General William Tecunseh Sherman noted as saying that "the quickest way to compel the Indians to settle down to civilized life was to send ten regiments of soldiers to the plains, with orders to shoot buffaloes until they became too scarce to support the redskins." -Lt. General John M. Schofield in his memoirs: "With my cavalry and carbined artillery encamped in front, I wanted no other occupation in life than to ward off the savage and kill off his food until there should no longer be an Indian frontier in our beautiful country."
In other words, John Gast's image of American Progress in his 1872 canvas:
It should go without saying that, if U.S. schools are not teaching the reality, good and bad, of this country's history, they are as guilty of malpractice as a drunken surgeon.
And let the bison run free.