Good grief! We decided to do Custer State Park today and see some bison.
We drove, and drove, and drove. Even went off the loop for several miles. No bison. We saw prairie dog towns, antelope, pronghorns, wild (actually quite tame) burros....no bison.
Stopped for lunch at this little lodge, then figured - eh - let's give it another shot. Drove and drove. And drove some more.
Finally - YAY! - there they were!