From the record
“The Carnegie Library in Sheldon, Iowa is a building from 1908. It was listed on the National Register of Historic Places in 1977.”
Wikipedia article Carnegie Library (Sheldon, Iowa), CC BY-SA 4.0.
One of 2 National Register listings published here for O'Brien County · listed in 1977 · category: Building · built in 1908, Beaux-Arts.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service · the Wikipedia article