From the record
“The White Horse Ranch, in Boyd County, Nebraska near Naper, Nebraska was founded in 1936. It was listed on the National Register of Historic Places in 1990.”
Wikipedia article White Horse Ranch (Naper, Nebraska), CC BY-SA 4.0.
One of 3 National Register listings published here for Boyd County · listed in 1990 · category: District.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service · the Wikipedia article