Elk Park Pass is on Interstate 15, five miles north of Butte, Montana. It is steep and should be avoided in the winter. The descent starts just south of Exit 133 in the middle of a huge grassy valley (Elk Park).
Of course, you could say that RVs should avoid traveling in the winter in the northern Rocky Mountains and I would agree. It goes double for steep roads in the winter.
In the summer, Elk Park Pass is merely a steep road but I think you should know what you are getting into before you go there. Really the road is very nice, wide, with four lanes in each direction.
In the winter expect snow and ice. The road is maintained well but melting snow will run across the road and turn to ice nightly making for very hazardous driving.
The descent southbound is nearly straight.
Expect large vehicles to be traveling at slow speeds relative to traffic or speed limits.
Montana interactive map for road conditions. MDT Travel and Weather
Elevation: 6352 feet
Length: 3 miles
Terrain: 6% grade southbound, no descent on north side of the pass.
Turns: This road is almost straight until you Interstate 15 merges with Interstate 90 east of Butte. At the end of the descent is the Interstate 15 – Interstate 90 split. Westbound traffic departs to the right.
Eastbound traffic should take precautions in that the eastbound off-ramp is a decreasing radius turn. I call this a dump truck turn which is usually preceded by a sign warning truck that roll-over is possible. The maximum speed for this turn in 25 miles-per-hour.
Eastbound lanes compress into a one-lane, with opposing traffic followed by an underpass and enter a decreasing radius right turn cloverleaf to join Interstate 90. The guard rail on the inside of the turn and the concrete barrier on the outside of the turn makes the path obvious. Near the end of the cloverleaf, the critical speed is 25 miles-per-hour. Enter this turn too fast, especially in the winter, and at a minimum, you will be against the concrete barrier — or if you make it all the way to the apex of the turn, you will have a runout across the median.
Turnouts: No side of the road turnouts
Turnaround locations: Exit 134 near the top, would make an easy turnaround.
Chain up areas: Not observed
Runaway truck ramps: None
Elk Park Pass, Our Experience
We drove over Elk Park Pass eastbound on our way to Rigby, Idaho on September 16, 2020. The road was dry and overall, other than slow speeds pertaining to the steepness of the grade we didn’t have any difficulty.
We joined Interstate 90 westbound and did not drive through the decreasing radius turn.
Here is our link to our interactive map. Bad Roads for RVs