Yellowstone National Park is well-known as the home of elk, bison, and grizzly bears, but visit in summer and you likely won't associate the park with bighorn sheep. That's because the sheep head for the cooler temperatures of the high country. But in winter they come down to the river valleys to escape the deepest snows and to forage.

One of the best spots in Yellowstone for viewing wildlife in winter is the Lamar Valley. There are two reasons for this. One is that the valley with the Lamar River flowing through it lures lots of wildlife -- bighorn sheep, bison, elk, coyotes, and wolves. The second is that the road through the valley between Mammoth Hot Springs and Cooke City, Montana, is plowed, providing easy access for your rig.