There are 12 CGs in Yellowstone NP, five operated by Xanterra and seven operated by the park. Mammoth is park-operated and located five miles from Gardiner and the North Entrance. It is FCFS. At 6,200 feet of elevation it is the lowest (and therefore generally the warmest) CG in the park. There are no hookups. It has 85 sites, flush toilets, water spigots and trash collection. Generators are allowed from 8 AM to 8 PM. Quiet Time is 10 PM to 7 AM. The cost is $20/night so I paid $10 (Senior Pass). It has no dump station but there is one in Gardiner, MT. There are no showers in the CG but they are available for a few dollars in the hotel in Mammoth Village, just a mile up the hill. The village also has a gas station, grocery store, restaurant and gift shop as well as the park's headquarters. The CG has many pull-throughs . Roads and pads are paved but in rough shape. I had to lift the curb side of the TrailManor about four inches. Part of the CG faces the main road into the park and therefore endures a great deal of traffic noise during the day and early evening. There is much less noise at the far end of the CG because it curves away from the road. Mammoth usually fills between 5 and 7 PM but stays available on many nights. We arrived at 4PM and got Site 18, a pull-through. Checkout time is 11 AM. The landscape is typical arid, semi desert, with sage, scrub grass and small trees. While many sites are a reasonable distance apart there isn't much privacy. We were fortunate to have two trees for shade -- many sites were in open sun. We used Mammoth as our base of operations while in Yellowstone, spending five nights there. Here is a photo of our campsite . Here is the view we had from our site.