American bison have made a triumphant return from the brink after being hunted nearly to extinction in the 1800s. While most bison these days are part of captive herds, a few locations have populations of free-roaming animals. Notable among these is Yellowstone National Park, where the number of bison ranges between 2,300 and 4,500.  Yellowstone is the only place in the U.S. where bison have lived continuously since before recorded history.