Overview and Getting There
The twin summits of Duncum Mountain are located 4.0 miles northeast of Medicine Mountain in the Big Horn Range of Wyoming. Forest Road 11, also known as Sheep Mountain Road, crosses between the summits at an elevation of over 9,750 feet and allows for easy access to both. As with a number of other peaks along the Medicine Wheel Passage whose summits are reached by relatively short hikes, the summit views are broad, vast, and beautiful.
This mountain is about two miles long from west to east, and the two summits mentioned above are almost exactly one mile apart. According to the topo map, the west summit is 9831 feet, which is one foot higher than the 9830 mark listed for the benchmark on the east summit. However, there is a rock pillar on the east summit that is several feet higher than the outcrop where the benchmark is located and it might be possible that the highest point on that mountain may be there instead; more on the pillar below...
From Lovell, Wyoming, take U.S. Highway 14A heading east for about 25.5 miles and turn left on Road 14, which is marked for Devils Canyon. To approach from Sheridan, Wyoming, follow Highway 14 to Burgess Junction, turn right on Highway 14A, and travel for about 18.5 miles. Stay on Road 14 for about 3 miles and turn right at the fork directing you to Sheep Mountain; this road climbs up and over Duncum Mountain.
The East Summit
To reach the east summit, park near the cattle guard and walk east along the fence for about 0.5 mile. The large rock pillars that litter the area around the top are quite impressive; the USGS benchmark is not obvious at first, but if you climb up the small rock outcrop just behind the stake driven in the ground, you will find it.
The summit pillar is 30+ feet high and dominates all of the other rocks around. I was not able to tell for sure if there was a cairn on top of it, but it did not look like it to me. The rock is very solid with small holds, but they are very sharp and were quite painful to climb on. The rock overhangs near the top around much of the pillar; obviously, I did not make a serious attempt to climb this formation. The climbing is definitely 5th-class and would be difficult to protect.
The West Summit
After driving over the cattle guard through the fence, continue around the curve and park near the highest point of the road. After a short scramble, you will be on the summit plateau; make for the highest rock cairn, which is fairly obvious. Like Sheep and Medicine Mountains, the layer of rock that makes up the whole top of the mountain is split all over with crevasses, some of which are 20-30 feet deep.
If you want a to do a slightly longer hike in this area, scramble down the south side of Duncum Mountain and walk the grassy ridge to the aptly named Cone Mountain, which provides another perspective on this beautiful area.
The total combined hiking distance to both summit areas is about 0.75 miles and 250 feet of elevation gain on Class 1 terrain, so this is a great mountain to do if you have very limited time in the area.