From the record
“The Plaza Blanca Historic District, in Plaza Blanca, New Mexico, United States, is a 19 acres (7.7 ha) historic district which was listed on the National Register of Historic Places in 1986.”
Wikipedia article Plaza Blanca Historic District, CC BY-SA 4.0.
One of 46 National Register listings published here for Rio Arriba County · listed in 1986 · category: District.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service