From the record
“Fort Clark Trading Post State Historic Site was once the home to a Mandan and later an Arikara settlement. Over the course of its history it also had two factories.”
Wikipedia article Fort Clark Trading Post State Historic Site, CC BY-SA 4.0.
One of 6 National Register listings published here for Mercer County · listed in 1986 · category: Site.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service