Mammoth Campground is an 85-site campground in Yellowstone National Park, open year-round. It is located near the park's ...

The 6 Best Yellowstone National Park Campgrounds for a Night in the Great Outdoors. ... It's also situated near the southern shore of Yellowstone Lake, and open from early June to mid-September.

But Canyon Campground has 17 sites (just $10 a night) are first come/first serve, and they sit near the Yellowstone River just 16 miles from the north entrance to the park.