From the record
“The Hancock County Courthouse is located in Garner, Iowa, United States. It was listed on the National Register of Historic Places in 1981 as a part of the County Courthouses in Iowa Thematic Resource.”
Wikipedia article Hancock County Courthouse (Iowa), CC BY-SA 4.0.
One of 9 National Register listings published here for Hancock County · listed in 1981 · category: Building.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service
