Developed in 1933, this appears to be a rather rare lookout cabin for the northwest states, a Region-5 (California) cab. It has a much steeper roof than most cabs. If anyone else has a better identification, let me know.
Challis National Forest
18 miles northeast of Stanley
Custer County, Idaho
Elevation 9753'
USGS Benchmark QA0724
USGS Benchmark QA0725

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Custer L.O. Custer in 2010
Photos courtesy of Jim Reid and Luke Channer