Petrified Forest Loop (Theodore Roosevelt National Park) Hiking Guide
In the remote northwest corner of the South Unit, the park says, is the third highest concentration of petrified wood in the United States: stumps of trees that grew here when this was swamp. A full day loop links the North and South Petrified Forest trails with a stretch of the Maah Daah Hey across open prairie. If you only want the wood, either section is about 1.5 miles from the parking area.
Permit: The Petrified Forest trailhead is outside the entrance stations, but Theodore Roosevelt's entrance fee applies year-round: $30 per private vehicle, $25 per motorcycle, or $15 per person traveling on foot, bicycle or horseback (age 16+), valid 7 days. Buy it online or by card in Medora. Overnight trips need a free backcountry permit from the South Unit Visitor Center.
How Long It Is
The park's figures don't quite agree: its trail table gives the loop as 10.3 miles and its Petrified Forest page says 10.4. Hiking Project maps 10.6 miles with about 601 feet of total climbing, and its overview calls it 10.5. Plan on roughly 10.5 miles and 5 to 6 hours, which is the park's estimate. For a shorter day, walk out to either petrified section and back, about 3 miles.
The Drive In Has Changed
Use the park's route. A section of Knutson Creek Road that older directions used was closed in 2025, and the Dickinson Press reported that the legal route roughly triples the distance from Medora, to about 31 miles. The park now sends visitors off I-94 at exit 10 toward Camels Hump Lake, then along county and ranch roads marked with posts; the turn-by-turn steps are on its Petrified Forest page. Expect about 50 minutes from Medora on dirt and gravel, and skip it after heavy rain.
On the Trail
From the lift gate behind the trailhead sign, Hiking Project describes a climb of about 175 feet in the first half mile onto a wide prairie, where the trail splits. The north branch is the hardest part of the loop, with a drop of about 300 feet and an immediate 300-foot climb before it meets the Maah Daah Hey; the north side also has the bigger cluster of wood. The Maah Daah Hey segment and most of the South Petrified Forest Trail are flat grassland. Leave every piece of petrified wood where it lies; removing it is illegal.
Water, Shade and Footing
There is little to no shade and no reliable water. The park asks for at least a liter per person per hour, which on a summer day here means a lot of water. Ticks, flies and biting insects are out in summer. Surfaces aren't maintained, and the clay can be extremely slick after rain. Bison and feral horses graze this end of the park; give them 25 yards or more.
Fee and Dog Rules
No booth stands at this trailhead, but the park says its entrance fee applies year-round. Buy a $30 weekly vehicle pass online or in Medora before you leave pavement. Pets are not allowed here. If your dog is coming, hike the Maah Daah Hey outside the park instead, on national grassland where dogs are allowed.
Hiking tips for Petrified Forest Loop (Theodore Roosevelt National Park)
- Follow the park's exit 10 directions, not old maps that use Knutson Creek Road.
- Carry at least a liter of water per person per hour; there is none on the loop.
- Do the north branch first, while you are fresh for its steep dip and climb.
- Photograph the petrified wood, but leave every piece where you find it.
- Skip the gravel approach and the clay trail after a heavy rain.
Nearby trails to explore
- Jones Creek, Lower Talkington and Lower Paddock Loop
- Wind Canyon Trail (Theodore Roosevelt National Park)
- Painted Canyon Trail (Theodore Roosevelt National Park)
Hike this trail with TrailMates
The Petrified Forest is a long drive on gravel and a long day on foot, so share both. Organize it in TrailMates, sort out carpools in the event's group chat, and head for the trailhead together. Download TrailMates on the App Store or Google Play.