From the record
“Denver and Rio Grande Western 168 is a T-12 class 4-6-0 "Ten-Wheeler" type narrow-gauge steam locomotive. It is one of twelve similar locomotives built for the Denver and Rio Grande Railroad (D&RG) by the Baldwin Locomotive Works (BLW) in 1883.”
Wikipedia article Rio Grande 168, CC BY-SA 4.0.
One of 13 National Register listings published here for Conejos County · listed in 1979 · category: Structure.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service