Yellowstone National Park, the first National Park in the world, is in my opinion, the Serengeti of the lower 48 States. It ranges over 2,200,000 acres and contains one of the most diverse arrays of wildlife found anywhere.
You cannot drive through the park in the winter and avoid seeing great numbers of bison and elk, thousands of each species. The winter is a special time to visit the park as there are fewer tourists and the wildlife is more accessible.
Coyotes trot along looking for easy prey. You can see big horn sheep and mountain goats adorning the rocky crags overlooking the various valleys. Mule deer and white tail deer often graze together. And nearby pronghorn antelope prancing through meadows.
Then there is the top of the food chain: the grey wolf, returned to the park in 1995-96. Elusive hunters, not often seen except through spotting scopes at great distances, they now number close to 100 after having been totally eliminated by 1926.