Short answers, pulled from the story.
By 1889, only 541 American bison remained in the United States, reduced from an estimated 60 million before the 1870s. The surviving animals were scattered across six tiny herds, five managed by private ranchers and one by the New York Zoological Park, plus a wild group of 25 in Yellowstone National Park.
Plains bison are the smaller subspecies, with a more rounded hump, while wood bison are larger and carry a taller, square hump. Wood bison are among the largest wild bovids in the world, surpassed in size only by the Asian gaur.
The U.S. government supported the destruction of bison herds as a strategy during the American Indian Wars, targeting the animal because it was the central resource for the traditional way of life of Plains Nations, providing food, hides for clothing and shelter, and bones and horns for tools.
As of 2011, estimates suggested only 15,000 to 25,000 genetically pure bison existed out of a total population of roughly 500,000 across private and public herds. Most herds carry at least some cattle DNA from crossbreeding that occurred during the 19th-century population bottleneck.
The American bison became the national mammal of the United States in 2016. The bison had previously appeared on the buffalo nickel from 1913 to 1938, and later featured on several state quarters including Kansas, North Dakota, Montana, and the Yellowstone National Park quarter.
The Texas State Bison Herd, also known as the Goodnight herd, was established by Charles Goodnight in the mid-1880s with five wild-caught calves and was donated to the State of Texas in 1997 with just 36 individuals. A 2004 population model gave it a 99% chance of extinction within 41 years without outside intervention, making it a key case study in the severe genetic consequences of extreme population bottlenecks.