From the record
“The Bridge over Burro Cañon, near Madrid, Colorado, was built in 1936. It carries Colorado State Highway 12, a main route linking La Veta with Trinidad, over an arroyo.”
Wikipedia article Bridge over Burro Cañon, CC BY-SA 4.0.
One of 26 National Register listings published here for Las Animas County · listed in 1985 · category: Structure · built in 1936.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service

