The National Bison Range
This attraction is located not far from St. Ignatius on Highway 212. ...19,000 acres of grassland are home to a variety of wildlife, including deer, pronghorn antelope, bighorn sheep, and a herd of 300-500 bison which, thanks to the efforts of conservationists, were saved from near-extinction in the earlier part of the 20th century. A dirt road that winds its way up a mountain allows visitors the opportunity to catch a glimpse of some of the wildlife which inhabit the range (such as this mule deer in the photo to the right.)
This photo doesn't do justice to the heavenly-looking real-life view I remember.
An easy trail at one point along the drive takes visitors to the crest of a hill overlooking the valley pictured above. The bighorn sheep at left were apparently visiting a salt lick strategically stationed to attract wildlife within viewing range.

(...but where were the 300-500 bison the range was named for?)