From the record
“The Salmon Mountain Lookout, on Salmon Mountain in the West Fork District of Bitterroot National Forest, near Darby, Idaho, was built in 1949. It was listed on the National Register of Historic Places in 2018.”
Wikipedia article Salmon Mountain Lookout, CC BY-SA 4.0.
One of 42 National Register listings published here for Idaho County · listed in 2018 · category: Building · built in 1949.
Sources: the Wikipedia article · the National Register database, National Park Service