From the record
“The Ant Flat Ranger Station is a site on the National Register of Historic Places located 2 miles south of Fortine, Montana in Kootenai National Forest. It was added to the Register on December 30, 1996.”
Wikipedia article Ant Flat Ranger Station, CC BY-SA 4.0.
One of 9 National Register listings published here for Lincoln County · listed in 1996 · category: Building.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service