So here are your last hints followed by the ANSWER at bottom.
That's right! Little Bighorn Battlefield National Monument located in the Crow Agency, Montana (near Billings) also known as the site of Custer's Last Stand.
Did we mention that the ONLY reason we stopped here was because Robert Redford MIGHT have been here while shooting the Horse Whisperer? The characters in the movie, Annie and Grace (mom and daughter) stop here on their trek to take Pilgrim, the horse, to see the horse whisperer (RR). RR wasn't even in the scene, but he was the producer so we thought he might have been here at some point. And, haha, as it turns out he MIGHT not. The battlefield was actually recreated on location elsewhere in Montana for the shooting. So, while we were looking for RR, we got a history lesson instead. The joke's on US!
Thanks for playing everyone!
The Road Dogs