The National Bison Range is near Ronan, Montana. Besides the bison
they have pronghorns
and elk, though the only elk we saw were the ones in this picture, and we didn't know we were seeing them until we enlarged it.
The animals live in a mostly natural habitat, as they did before we got here. Much more interesting than a zoo. The bison like to wallow in sand pits, to remove bugs from their fur
Outside the park is a roadside restaurant where they serve – of course – bison burgers. Very tasty.
The park includes some small mountains, which you drive up and down and around, and some short walks to scenic views of the surrounding valleys and mountains.
In the visitor center you can learn all about the bison and their history in the US. It's pretty far off the beaten path for most tourists, but when you're on the way from here to there in your RV, it's not that hard to get to.
More pictures here.