From the record
“The Eagle Guard Station is a site on the National Register of Historic Places located about 11 miles west of Townsend, Montana. It was added to the Register on September 20, 2001.”
Wikipedia article Eagle Guard Station, CC BY-SA 4.0.
One of 11 National Register listings published here for Broadwater County · listed in 2001 · category: Building.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service