Mammoth Campground Review: Yellowstone's Only Year-Round Campground

Mammoth Campground is Yellowstone’s only year-round campground: 82 dry sites at $25 a night, no hookups, a 45-foot combined length limit from May through mid-October and 30 feet in winter, booked on Recreation.gov in season and first-come, first-served from October 15 through April 1. It sits just below Mammoth Hot Springs near the North Entrance at roughly 6,200 feet, the lowest and mildest campground in the park.

That low elevation is the reason it can stay open when Canyon and Grant are under snow, and it is also why Mammoth is the campground we send early-season and late-season RVers to. This review covers what the campground is actually like, who fits, and how it compares to Yellowstone’s other options.

We verified sites, fee, season, limits and reservation rules against the NPS Yellowstone campground table for 2026. For the park-wide picture, our Yellowstone RV camping guide covers all twelve campgrounds.

Quick answer: Mammoth is a $25, no-hookup, 82-site campground open all year. Rigs up to 45 feet combined fit in season, 30 feet in winter. Book on Recreation.gov six months out for April through mid-October; from October 15 to April 1 just show up. Elk walk through the loops most days, and it is the closest in-park camping to Gardiner, Lamar Valley and the northern range.

Mammoth Campground at a glance#

Spec	Detail (NPS 2026 table)
Sites	82 (some accessible; limited hiker/biker)
Fee	$25 per night
Hookups	None (dry camping)
Max length	45 ft combined May–mid-Oct; 30 ft mid-Oct–April
Reservations	Recreation.gov (6-month window); first-come Oct 15–Apr 1
Season	Year-round
Elevation	About 6,200 ft
Toilets	Flush and pit toilets listed
Dump station	Yes
Generators	Allowed, posted daytime hours
Showers	Not on site; Mammoth Hot Springs Hotel when operating

What Mammoth is like#

Mammoth is a hillside campground on the north side of the Mammoth Hot Springs developed area, five miles from the North Entrance at Gardiner, Montana. Instead of the lodgepole forest that surrounds most Yellowstone campgrounds, you get open sagebrush, scattered juniper and Douglas fir, and views across the Gardner River canyon. It feels more like high desert than mountain forest, which some campers love and others find exposed.

The loop is compact and sloped, with a mix of back-in and a few pull-through pads. Elk are the defining feature: the Mammoth herd wanders through the campground and the hotel lawns constantly, and in the September and October rut a bull elk bugling between the sites at 5 a.m. is the standard wake-up. Give them room; rangers close sections of the area during the rut when bulls get aggressive.

The developed area up the hill has the Albright Visitor Center, a general store, the Mammoth Hot Springs Hotel and its dining room (seasonal), a gas station, and the terraces themselves. Gardiner, five miles down the road, has groceries, restaurants, fuel and a handful of private RV parks with hookups.

Hookups, water and power#

There are no hookups at Mammoth. Every site is dry, like every campground in Yellowstone except Fishing Bridge RV Park. What the campground does have:

• Potable water and flush toilets (the NPS table also lists pit toilets); expect reduced services in winter and confirm water availability before a cold-season stay.
• A dump station, so you can arrive with empty tanks and leave clean.
• Generator use during posted daytime hours. Yellowstone’s park-wide rule is roughly 8 a.m. to 8 p.m. with a 60-decibel limit at 50 feet; check the posted hours at the loop.

If you are dry camping for more than a couple of nights, our RV power without hookups guide covers solar and battery sizing for exactly this kind of stay. Mammoth’s lower elevation means less overnight furnace load than Canyon or Grant, which helps.

Rig size: 45 feet in summer, 30 in winter#

The NPS lists a 45-foot combined length limit from May through mid-October and a 30-foot combined limit from mid-October through April. In practice, the campground is small and sloped, and not every site fits 45 feet; Recreation.gov will only offer you sites that match the equipment length you enter, so enter your true combined length. Older references to a “40-foot” limit at Mammoth are the previous figure; the current table says 45.

For a big fifth wheel or Class A with a toad, Mammoth is workable in summer but not roomy. If you are over 40 feet and want easier maneuvering, Bridge Bay, Madison or Fishing Bridge are more comfortable, and our national park RV rig size limits guide shows how the Yellowstone campgrounds stack up.

Reservations: two systems, one campground#

Mammoth is on Recreation.gov, not the Yellowstone National Park Lodges system, which for 2026 handles Fishing Bridge, Bridge Bay, Canyon, Grant and Madison. Two things follow:

• April through mid-October: reserve on Recreation.gov, rolling six-month window. Summer weekends sell out; shoulder weeks in May and October are usually available.
• October 15 through April 1: first-come, first-served, and the only walk-up camping in the park. Arrive by early afternoon on autumn weekends; winter weekdays are wide open.

Our Yellowstone campground reservations guide explains the 2026 split and the 2027 move of every campground onto Recreation.gov.

Winter camping at Mammoth#

From November through March, Mammoth is the only place to sleep in an RV inside Yellowstone. The road from Gardiner to Mammoth and on to Cooke City through Lamar Valley is the only park road plowed for wheeled vehicles all winter, so a winter stay at Mammoth means Lamar wolf-watching at dawn without a snowcoach. Expect:

• Reduced services: assume limited toilets and no reliable running water, so bring full fresh tanks and do not count on the dump station in freezing weather.
• A 30-foot combined limit; the winter loop is small.
• Nighttime lows well below zero Fahrenheit in January. A four-season rig, heated tank pads and a serious propane budget are not optional.
• Sites are $25 and first-come; you will rarely need to compete for one.

This is a niche use, but for photographers and wolf-watchers it is one of the best winter RV bases in any national park.

What to do from Mammoth Campground#

Mammoth is the northern range’s campground, and its geography favors a specific set of days.

• Mammoth Hot Springs Terraces. The travertine terraces are a five-minute drive or a stiff walk up the hill; the Upper Terrace Drive is a short one-way loop and the boardwalks are best in early morning light. Do this the evening you arrive.
• Lamar Valley. Leave the campground before dawn, drive east through Tower Junction and into Lamar for bison, wolves and grizzlies. It is about an hour to the heart of the valley, and the pullouts fill with spotting scopes by first light. This is the reason wildlife-focused campers pick Mammoth over anything else.
• Boiling River area and the Gardner River. The Mammoth-to-Gardiner road follows the river canyon; the roadside pullouts are reliable spots for bighorn sheep and pronghorn.
• Norris and the geyser basins. Norris Geyser Basin is about 21 miles south via Indian Creek and Sheepeater Cliff. Old Faithful is roughly 50 miles and a full day out and back.
• Gardiner. Five miles north through the Roosevelt Arch, with restaurants, groceries, fuel, and rafting on the Yellowstone River. It is the easiest resupply town for any in-park campground.

Wildlife rules that are specific to Mammoth#

The elk herd is a daily presence in the campground and the developed area. In the fall rut, roughly mid-September through October, bulls charge people who get close, and rangers cordon off areas of the hotel lawns and campground. Stay 25 yards from elk and bison and 100 yards from bears and wolves, and never walk between a bull and his cows. Mammoth is also grizzly country; food, coolers, stoves and toiletries go inside the RV or vehicle at all times when not in use.

Site tips#

• The loop is sloped and sites are back-in with limited pull-through inventory; bring leveling blocks.
• Sites at the outer edge of the loop face the sagebrush hillside and are quieter; inner sites are closer to the road and toilets.
• Shade is scarce compared with the forested campgrounds, which is welcome in a cool May and hot in an August afternoon; an awning matters here.
• The lower elevation and open terrain mean better solar exposure than at Canyon or Madison, which helps for a dry-camping stay.

How Mammoth compares to Yellowstone’s other campgrounds#

Campground	Hookups	Sites	Max length	Season	Booking (2026)
Mammoth	None	82	45 ft summer / 30 ft winter	Year-round	Recreation.gov; FCFS Oct 15–Apr 1
Fishing Bridge RV Park	Full	310	Up to 95 ft	May–Oct	Yellowstone NP Lodges
Madison	None	See NPS table	60 ft	May–Oct	Yellowstone NP Lodges
Indian Creek	None	~70	35 ft	June–Sept	Recreation.gov
Tower Fall	None	31	30 ft	May–Sept	Recreation.gov

Mammoth’s edge is season length and the northern range. Its weakness is that it is in the far northwest corner: Old Faithful is about 50 miles and 90 minutes away, and the lake and canyon are similar. If you want to see the whole park from one campground, Madison or Canyon are more central; see our Yellowstone campgrounds compared guide for that ranking. If you mainly want Lamar Valley wildlife, the Mammoth terraces and the northern loop, Mammoth is the right base and Tower Fall (30 feet, hairpin approach) is the only alternative closer to Lamar.

Nearby with hookups: Gardiner and West Yellowstone#

If you need shore power for part of the trip, the private parks in Gardiner, five miles north of the campground, are the closest full-hookup sites to Mammoth. West Yellowstone, at the West Entrance, has more choices and a bigger town but is a 90-minute drive; our West Yellowstone RV parks guide covers those. A common pattern is two dry nights at Mammoth for the northern range, then a hookup reset in Gardiner or West Yellowstone before Madison or Fishing Bridge.

Verdict#

Mammoth Campground is Yellowstone’s most useful odd one out: low, mild, cheap, open all year, and full of elk. Book it for shoulder-season and winter trips, for Lamar Valley access, and for the days you cannot get anything else. Do not book it expecting hookups, showers or a central location. At $25 a night with a dump station and a 45-foot summer limit, it is one of the best-value RV sites in any national park, provided your rig can go without power. For more Wyoming camping, start at our Wyoming hub.