Campground · WY
Mammoth Campground (Yellowstone)
WY · Yellowstone National Park
Booking is hardest here in May (4/10) and easiest in January (2/10). Pick a month below for the full breakdown.
Booking difficulty by month
Midweek tip: in the busiest month (May), arrivals are lightest on Wednesday — shift your dates to improve your odds.
When reservations open
Booking window
Reservations open on a rolling 6-month window at 7:00 AM America/New York.
For example, sites for January 15, 2027 become bookable on July 15, 2026. Set a reminder a few minutes before release for the best shot.
Standard Recreation.gov 6-month rolling window: sites become bookable 6 months before arrival at 7:00 AM ET.
Sites & amenities
- 87 RV sites
- 5 accessible sites
- Max RV length 99 ft
Activities: AMPHITHEATER, BIRDING, CAMPING, CROSS COUNTRY SKIING, CULTURAL ACTIVITIES, FISHING, HIKING, HISTORIC & CULTURAL SITE, INTERPRETIVE PROGRAMS, SKIING, VISITOR CENTER, WILDLIFE VIEWING, AUTO TOURING